6. Giải toán Tiểu học bằng Phương pháp giả thiết tạm

<p> </p><div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFMftAGyKVO00vU1ElEMKDT5rwiFueab30mfksm_Rv07JJ54O_yD4bJTam7qmp9erFYuJgUOcFpIBqeOfU65IfqDfhE-ZgeHGpoBlKOHujXiMzmT0prl9PVMEq8pTdOuAeZjGcXAu42PRlnHWpVMa9CSEN_kHHjeMXqxr8j6UQObObc3S1-WA84bJxH8aL/s600/t5.jpeg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" data-original-height="549" data-original-width="600" height="293" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjFMftAGyKVO00vU1ElEMKDT5rwiFueab30mfksm_Rv07JJ54O_yD4bJTam7qmp9erFYuJgUOcFpIBqeOfU65IfqDfhE-ZgeHGpoBlKOHujXiMzmT0prl9PVMEq8pTdOuAeZjGcXAu42PRlnHWpVMa9CSEN_kHHjeMXqxr8j6UQObObc3S1-WA84bJxH8aL/s320/t5.jpeg" width="320" /></a></div><div class="separator" style="clear: both; text-align: center;"><br /></div><p></p><h1 style="--fontsize: 33px; --fontweight: 700; --lineheight: 1.5; background-color: #fbfbfb; border: none; box-sizing: border-box; color: var(--heading-color, var(--heading-1-color, var(--headings-color))); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: var(--fontSize); font-weight: var(--fontWeight); line-height: var(--lineHeight); margin-bottom: calc(var(--has-content-spacing, 1)*(0.3em + 10px)); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: var(--content-spacing); max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));">Phương pháp giả thiết tạm giải toán 5, toán 4</h1><div class="separator" style="clear: both;"><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Phương pháp giả thiết tạm là một trong những phương pháp giải toán quan trọng ở bậc tiểu học, và cả THCS, khi mà các em học sinh chưa được học khái niệm hệ phương trình.</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Xem thêm</p><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;"><a href="https://o2.edu.vn/cac-bai-toan-ve-trung-binh-cong-lop-4/" style="--textdecoration: underline; box-sizing: border-box; text-decoration: var(--has-link-decoration, var(--textDecoration, none)); transition: var(--transition);">CÁC BÀI TOÁN VỀ TRUNG BÌNH CỘNG LỚP 4</a></li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;"><a href="https://o2.edu.vn/120-bai-toan-thi-violympic-lop-5/" style="--textdecoration: underline; box-sizing: border-box; text-decoration: var(--has-link-decoration, var(--textDecoration, none)); transition: var(--transition);">120 BÀI TOÁN THI VIOLYMPIC  LỚP 5</a></li></ul><h2 style="--fontsize: 30px; --fontweight: 700; --lineheight: 1.5; background-color: #fbfbfb; border: none; box-sizing: border-box; color: var(--heading-color, var(--heading-2-color, var(--headings-color))); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: var(--fontSize); font-weight: var(--fontWeight); line-height: var(--lineHeight); margin-bottom: calc(var(--has-content-spacing, 1)*(0.3em + 10px)); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: var(--content-spacing); max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">1. Phương pháp giả thiết tạm là gì?</h2><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Phương pháp giả thiết tạm thường dùng đối với các bài toán cần tìm 2 đại lượng chưa biết, mà giữa 2 đại lượng này có mối liên hệ hơn kém nhau một số đơn vị (như vận tốc của hai đối tượng chuyển động, năng suất của hai máy/người khác nhau, hai loại vé giá tiền khác nhau, số chân gà và chân chó…)</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Để sử dụng phương pháp giả thiết tạm, chúng ta thử đặt ra một trường hợp không xảy ra, không phù hợp với điều kiện bài toán, một khả năng không có thật thậm chí một tình huống vô lí (chính vì vậy mà phương pháp này đòi hỏi người giải toán sức tưởng tượng phong phú, óc suy luận linh hoạt… ) Tất nhiên giả thiết ấy chỉ tạm thời, nhưng phải tìm được giả thiết ấy, nhằm đưa bài toán về một tình huống quen thuộc, đã biết cách giải hoặc dựa trên cơ sở đó để tiến hành lập luận mà suy ra được cái phải tìm.</p><div class="code-block code-block-4" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px auto; max-width: var(--default-editor, var(--block-max-width)); text-align: center; width: var(--default-editor, var(--block-width));"></div><h2 style="--fontsize: 30px; --fontweight: 700; --lineheight: 1.5; background-color: #fbfbfb; border: none; box-sizing: border-box; color: var(--heading-color, var(--heading-2-color, var(--headings-color))); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: var(--fontSize); font-weight: var(--fontWeight); line-height: var(--lineHeight); margin-bottom: calc(var(--has-content-spacing, 1)*(0.3em + 10px)); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: var(--content-spacing); max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">2. Các ví dụ về phương pháp giả thiết tạm</h2><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Ví dụ 1. </strong>Xét bài toán cổ sau đây:</p><div class="code-block code-block-5" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px auto; max-width: var(--default-editor, var(--block-max-width)); text-align: center; width: var(--default-editor, var(--block-width));"></div><blockquote style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><p style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: 0px; margin-right: 0px; margin-top: 0px; padding: 0px; text-align: inherit;">“Vừa gà vừa chó,<br style="box-sizing: border-box;" />Ba mươi sáu con,<br style="box-sizing: border-box;" />Bó lại cho tròn,<br style="box-sizing: border-box;" />Một trăm chân chẵn”</p></blockquote><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Hỏi có bao nhiêu con gà và bao nhiêu con chó?</p><div class="code-block code-block-6" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px auto; max-width: var(--default-editor, var(--block-max-width)); text-align: center; width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><img alt="vua-ga-vua-cho-phuong-phap-gia-thiet-tam" class="aligncenter size-full wp-image-29438" decoding="async" height="400" sizes="(max-width: 620px) 100vw, 620px" src="https://o2.edu.vn/wp-content/uploads/2020/11/vua-ga-vua-cho-phuong-phap-gia-thiet-tam.jpg" srcset="https://o2.edu.vn/wp-content/uploads/2020/11/vua-ga-vua-cho-phuong-phap-gia-thiet-tam.jpg 620w, https://o2.edu.vn/wp-content/uploads/2020/11/vua-ga-vua-cho-phuong-phap-gia-thiet-tam-300x194.jpg 300w" style="border: none; box-sizing: border-box; clear: both; display: block; font-size: inherit; height: auto; line-height: inherit; margin: 0px auto; max-width: 100%; padding: 0px; text-align: center; vertical-align: middle;" title="Phương pháp giả thiết tạm giải toán tiểu học 1" width="620" /></p><div class="code-block code-block-14" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px auto; max-width: var(--default-editor, var(--block-max-width)); text-align: center; width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"></p><div class="code-block code-block-7" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Phân tích.</strong> Đây là bài toán cổ quen thuộc ở nhiều nước. Rõ rằng là 36 con không thể là toàn chó cả hay toàn là gà cả. Bởi vì, nếu như thế, thì số chân sẽ là <span class="MathJax" id="MathJax-Element-1-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-1" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 6.468em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.552em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1005.5em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-2" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-3" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">4</span><span class="mo" id="MathJax-Span-4" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">×</span><span class="mn" id="MathJax-Span-5" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">36</span><span class="mo" id="MathJax-Span-6" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-7" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">144</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (chân) hoặc <span class="MathJax" id="MathJax-Element-2-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-8" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.822em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.013em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.96em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-9" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-10" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mo" id="MathJax-Span-11" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">×</span><span class="mn" id="MathJax-Span-12" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">36</span><span class="mo" id="MathJax-Span-13" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-14" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">72</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (chân), đều không phù hợp với giả thiết bài toán.</p><div class="code-block code-block-8" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Nhưng ta lại giả thiết rằng có trường hợp ấy, để từ chênh lệch về số chân của toàn bộ tổng số các con vật với sự chênh lệch về số chân của từng con chó với gà, ta suy ra số con vật mỗi loại.</p><div class="code-block code-block-9" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Lời giải.</strong></p><div class="code-block code-block-10" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Giả sử 36 con toàn là gà cả. Như vậy, số chân chỉ có là:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-3-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-15" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.121em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 4.421em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.37em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-16" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-17" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mi" id="MathJax-Span-18" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Math-italic; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">x</span><span class="mn" id="MathJax-Span-19" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">36</span><span class="mo" id="MathJax-Span-20" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-21" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">72</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (chân)</p><div class="code-block code-block-11" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Số chân bị hụt đi là: <span class="MathJax" id="MathJax-Element-4-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-22" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 6.414em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.498em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1005.45em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-23" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-24" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">100</span><span class="mo" id="MathJax-Span-25" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-26" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">72</span><span class="mo" id="MathJax-Span-27" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-28" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">28</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (chân).</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Sở dĩ bị hụt như vậy là do mỗi con chó không được tính đủ 4 chân mà bị tính hụt đi:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-5-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-29" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 4.098em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 3.505em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1003.45em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-30" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-31" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">4</span><span class="mo" id="MathJax-Span-32" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-33" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mo" id="MathJax-Span-34" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-35" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (chân)</p><div class="code-block code-block-12" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Ta thấy cứ mỗi một con chó bị tính thiếu đi 2 chân, mà tất cả bị thiếu <span class="MathJax" id="MathJax-Element-6-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-36" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 1.188em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 1.026em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1000.97em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-37" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-38" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">28</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> chân so với giả thiết, tức là có <span class="MathJax" id="MathJax-Element-7-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-39" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.391em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 4.636em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.58em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-40" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-41" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">28</span><span class="mo" id="MathJax-Span-42" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">:</span><span class="mn" id="MathJax-Span-43" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mo" id="MathJax-Span-44" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-45" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">14</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> con chó.</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Suy ra, số con gà là <span class="MathJax" id="MathJax-Element-8-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-46" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.822em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.013em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.96em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-47" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-48" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">36</span><span class="mo" id="MathJax-Span-49" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-50" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">14</span><span class="mo" id="MathJax-Span-51" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-52" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">22</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (con).</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">Các em học sinh có thể giả sử 36 con toàn là chó cả, thì cũng tìm được đáp số tương tự.</p><div class="code-block code-block-13" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Ví dụ 2. </strong>Lớp có 32 bạn tham gia chuyển gạch vụn làm kế hoạch nhỏ bằng xe cải tiến và quang gánh. Xe cải tiến cần bốn người một xe, còn quang gánh thì hai bạn khiêng một chiếc. Vừa xe cải tiến vừa quang gánh có tất cả 13 dụng cụ. Hỏi có mấy xe cải tiến và mấy chiếc quang gánh?</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Hướng dẫn.</strong></p><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Giả sử 13 dụng cụ đều là xe cải tiến cả. Khi đó số người cần có là bao nhiêu?</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Tính số người dôi ra, tính số người theo một quang gánh được tính dôi ra. Từ đó, tính số dụng cụ mỗi loại.</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Ví dụ 3. </strong>Một quầy bán hàng có 48 gói kẹo gồm loại 0,5 kg; loại 0,2 kg và loại 0,1 kg. Khối lượng cả 48 gói là 9 kg. Hỏi mỗi loại có bao nhiêu gói (biết số gói loại 0,1 kg gấp 3 lần số gói loại 0,2 kg).</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Hướng dẫn.</strong></p><div class="code-block code-block-17" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px auto; max-width: var(--default-editor, var(--block-max-width)); text-align: center; width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Vì số gói loại 0,1 kg gấp 3 lần số gói loại 0,2 kg nên cứ có 1 gói loại 0,2 kg thì có 3 gói loại 0,1 kg.</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Tổng khối lượng 1 gói 0,2 kg và 3 gói 0,1 kg là</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-9-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-53" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 9.216em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 7.923em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1007.87em, 2.751em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-54" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-55" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">0</span><span class="mo" id="MathJax-Span-56" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">,</span><span class="mn" id="MathJax-Span-57" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mo" id="MathJax-Span-58" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">+</span><span class="mn" id="MathJax-Span-59" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">0</span><span class="mo" id="MathJax-Span-60" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">,</span><span class="mn" id="MathJax-Span-61" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">1</span><span class="mi" id="MathJax-Span-62" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Math-italic; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">x</span><span class="mn" id="MathJax-Span-63" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">3</span><span class="mo" id="MathJax-Span-64" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-65" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">0</span><span class="mo" id="MathJax-Span-66" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">,</span><span class="mn" id="MathJax-Span-67" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">5</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 1.128em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.309em; width: 0px;"></span></span></nobr></span>(kg)</p><div class="code-block code-block-18" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Giả sử tất cả các gói kẹo đều là loại mới 0,5 kg thì sẽ có tất cả:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-10-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-68" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.876em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.067em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1005.01em, 2.751em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-69" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-70" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">9</span><span class="mo" id="MathJax-Span-71" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">:</span><span class="mn" id="MathJax-Span-72" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">0</span><span class="mo" id="MathJax-Span-73" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">,</span><span class="mn" id="MathJax-Span-74" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">5</span><span class="mo" id="MathJax-Span-75" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-76" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">18</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 1.128em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.309em; width: 0px;"></span></span></nobr></span>(gói)</p><div class="code-block code-block-19" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Nếu như vậy sẽ còn thiếu:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-11-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-77" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.822em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.013em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.96em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-78" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-79" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">48</span><span class="mo" id="MathJax-Span-80" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-81" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">18</span><span class="mo" id="MathJax-Span-82" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-83" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">30</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span>(gói)</p><div class="code-block code-block-20" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Còn thiếu 30 gói là do ta đã tính 4 gói (1 gói loại 0,2 kg và 3 gói loại 0,1 kg) thành 1 gói. Mỗi lần như vậy số gói sẽ thiếu đi:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-12-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-84" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 4.098em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 3.505em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1003.45em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-85" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-86" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">4</span><span class="mo" id="MathJax-Span-87" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-88" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">1</span><span class="mo" id="MathJax-Span-89" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-90" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">3</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (gói)</p><div class="code-block code-block-21" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Số gói cần phải thay là: <span class="MathJax" id="MathJax-Element-13-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-91" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.391em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 4.636em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1004.58em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-92" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-93" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">30</span><span class="mo" id="MathJax-Span-94" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">:</span><span class="mn" id="MathJax-Span-95" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">3</span><span class="mo" id="MathJax-Span-96" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-97" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">10</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span>(gói)</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Suy ra số gói 0,5 kg là <span class="MathJax" id="MathJax-Element-14-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-98" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.229em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 4.475em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1004.42em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-99" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-100" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">18</span><span class="mo" id="MathJax-Span-101" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-102" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">10</span><span class="mo" id="MathJax-Span-103" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-104" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">8</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (gói 0,5kg)</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Cứ 10 gói 0,2 kg thì có số gói 0,1 kg là <span class="MathJax" id="MathJax-Element-15-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-105" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.822em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.013em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.565em, 1004.96em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-106" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-107" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">10</span><span class="mo" id="MathJax-Span-108" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">×</span><span class="mn" id="MathJax-Span-109" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">3</span><span class="mo" id="MathJax-Span-110" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-111" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">30</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (gói 0,1kg)</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Đáp số: 0,5kg có 8 gói; 0,2kg có 10 gói; 0,1kg có 30 gói.</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Ví dụ 4. </strong>Có một số lít dầu hỏa, nếu đổ vào các can 6 lít thì vừa hết. Nếu đổ vào các can 10 lít thì thừa 2 lít và số can giảm đi 5 can. Hỏi có bao nhiêu lít dầu?</p><div class="code-block code-block-22" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Hướng dẫn. </strong></p><div class="code-block code-block-23" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Nếu đổ đầy số can 10 lít bằng với số can 6 lít thì còn thiếu:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-16-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-112" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 7.223em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 6.199em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1006.14em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-113" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-114" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">10</span><span class="mo" id="MathJax-Span-115" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">×</span><span class="mn" id="MathJax-Span-116" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">5</span><span class="mo" id="MathJax-Span-117" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-118" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">2</span><span class="mo" id="MathJax-Span-119" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-120" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">48</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (lít)</p><div class="code-block code-block-24" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Thiếu 48 lít này do mỗi can 6 lít ít hơn <span class="MathJax" id="MathJax-Element-17-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-121" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 4.636em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 3.99em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1003.94em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-122" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-123" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">10</span><span class="mo" id="MathJax-Span-124" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">–</span><span class="mn" id="MathJax-Span-125" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.164em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">6</span><span class="mo" id="MathJax-Span-126" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-127" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">4</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> lít so với can 10 lít.</li><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Suy ra, số can 6 lít là:</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-18-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-128" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.391em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 4.636em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.58em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-129" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-130" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">48</span><span class="mo" id="MathJax-Span-131" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">:</span><span class="mn" id="MathJax-Span-132" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">4</span><span class="mo" id="MathJax-Span-133" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-134" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">12</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (can)</p><div class="code-block code-block-25" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><ul style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; list-style-type: var(--listStyleType, disc); margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding-inline-start: var(--listIndent); padding: 0px; width: var(--default-editor, var(--block-width));"><li style="border: none; box-sizing: border-box; font-size: inherit; line-height: inherit; margin: 0px; padding: 0px; text-align: inherit;">Số lít dầu là</li></ul><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; text-align: center; width: var(--default-editor, var(--block-width));"><span class="MathJax" id="MathJax-Element-19-Frame" style="border: 0px; box-sizing: border-box; direction: ltr; display: inline; float: none; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; overflow-wrap: normal; padding: 0px; text-align: left; white-space: nowrap; word-spacing: normal;" tabindex="0"><nobr style="border: 0px; box-sizing: border-box; line-height: normal; margin: 0px; max-height: none; max-width: none; min-height: 0px; min-width: 0px; padding: 0px; transition: none 0s ease 0s; vertical-align: 0px;"><span class="math" id="MathJax-Span-135" style="border: 0px; box-sizing: border-box; display: inline-block; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 5.822em;"><span style="border: 0px; box-sizing: border-box; display: inline-block; font-size: 18.56px; height: 0px; line-height: normal; margin: 0px; padding: 0px; position: relative; transition: none 0s ease 0s; vertical-align: 0px; width: 5.013em;"><span style="border: 0px; box-sizing: border-box; clip: rect(1.511em, 1004.96em, 2.535em, -999.997em); left: 0em; line-height: normal; margin: 0px; padding: 0px; position: absolute; top: -2.368em; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mrow" id="MathJax-Span-136" style="border: 0px; box-sizing: border-box; display: inline; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;"><span class="mn" id="MathJax-Span-137" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px;">6</span><span class="mo" id="MathJax-Span-138" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">×</span><span class="mn" id="MathJax-Span-139" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.218em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">12</span><span class="mo" id="MathJax-Span-140" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">=</span><span class="mn" id="MathJax-Span-141" style="border: 0px; box-sizing: border-box; display: inline; font-family: MathJax_Main; line-height: normal; margin: 0px; padding: 0px 0px 0px 0.272em; position: static; transition: none 0s ease 0s; vertical-align: 0px;">72</span></span><span style="border: 0px; box-sizing: border-box; display: inline-block; height: 2.373em; line-height: normal; margin: 0px; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: 0px; width: 0px;"></span></span></span><span style="border-bottom-style: initial; border-color: initial; border-image: initial; border-left-style: solid; border-right-style: initial; border-top-style: initial; border-width: 0px; box-sizing: border-box; display: inline-block; height: 0.941em; line-height: normal; margin: 0px; overflow: hidden; padding: 0px; position: static; transition: none 0s ease 0s; vertical-align: -0.059em; width: 0px;"></span></span></nobr></span> (lít)</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Ví dụ 5.</strong> Một cái sọt có thể đựng đầy 14 kg táo hoặc đựng đầy 21 kg mận. Người ta đã đổ đầy sọt cả táo lẫn mận. Tính ra sọt nặng 18 kg và giá tiền cả sọt là 30.000 đồng. Hãy tính giá tiền 1 kg táo và 1 kg mận, biết trong 18 kg đó số tiền táo và mận bằng nhau.</p><h2 style="--fontsize: 30px; --fontweight: 700; --lineheight: 1.5; background-color: #fbfbfb; border: none; box-sizing: border-box; color: var(--heading-color, var(--heading-2-color, var(--headings-color))); font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: var(--fontSize); font-weight: var(--fontWeight); line-height: var(--lineHeight); margin-bottom: calc(var(--has-content-spacing, 1)*(0.3em + 10px)); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: var(--content-spacing); max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));">3. Bài tập sử dụng phương pháp giả thiết tạm</h2><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 1.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Huy mua 15 quyển vở gồm 2 loại hết tất cả 100 000 đồng. Biết giá vở dày là 8000 đồng một quyển và giá vở mỏng là 6000 đồng một quyển. Tính số vở mỗi loại Huy đã mua.</span></p><div class="code-block code-block-28" style="background-color: #fbfbfb; box-sizing: border-box; clear: both; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; margin: 8px 0px; max-width: var(--default-editor, var(--block-max-width)); width: var(--default-editor, var(--block-width));"></div><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 2. </strong><span class="fontstyle2" style="box-sizing: border-box;">Trong 1 bài kiểm tra, tất cả học sinh trong lớp đều được điểm 7 hoặc 8. Tổng số điểm của lớp là 336. Tính số học sinh được điểm 7, số học sinh được điểm 8. Biết tổng số học sinh là số chia hết cho 5.</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 3</strong><span class="fontstyle2" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">.</strong> Có 18 ô tô gồm 3 loại: Loại 4 bánh chở được 5 tấn, loại 6 bánh chở được 6 tấn và loại 8 bánh chở được 6 tấn. 18 xe đó chở được tất cả 101 tấn hàng, và có tất cả 106 bánh xe. Hỏi mỗi loại có bao nhiêu xe?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 4</strong><span class="fontstyle2" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">.</strong> Có 1120 quả vừa cam vừa quýt được đựng trong các sọt. Biết mỗi sọt cam đựng 75 quả, mỗi sọt quýt đựng 179 quả và số sọt cam ít hơn số sọt quýt là 2 sọt. Hỏi có bao nhiêu sọt cam, bao nhiêu sọt quýt?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 5</strong><span class="fontstyle2" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">.</strong> Một người đã mua cho cơ quan 30 vé xem đá bóng hết tất cả 2 150 000 đồng, gồm 3 loại: 50 000 đồng, 80 000 đồng và 120 000 đồng. Hỏi mỗi loại người đó đã mua bao nhiêu vé? Biết số vé loại 50 000 đồng gấp 3 lần số vé loại 120 000 đồng.</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 6.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Vòi thứ nhất chảy một mình trong 4 giờ thì đẩy bể, vòi thứ hai chảy một mình trong 6 giờ thì đầy bể. Người ta vặn vòi thứ nhất chảy trước, sau đó khóa lại để vòi thứ hai chảy tiếp thì hết tổng cộng 5 giờ. Hỏi mỗi vòi đã chảy hết bao lâu?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 7</strong><span class="fontstyle2" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">.</strong> Trong một giải bóng đá có bốn đội bóng (mỗi đội đều đá 1 trận với các đội còn lại để tính điểm), tổng số điểm của bốn đội là 16 điểm. Hỏi có mấy trận phân biệt thắng – thua, mấy trận hòa biết mỗi trận đấu thì đội thắng được 3 điểm, thua 0 điểm, trận hòa mỗi đội được 1 điểm?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 8.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Khối học sinh lớp 5 gồm 480 em đi tham quan bằng 2 loại xe ô tô: loại chở được 50 người và loại chở được 40 người. Các em đã ngồi trên 10 xe ô tô thì vừa đủ chỗ. Hỏi có bao nhiêu xe mỗi loại?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 9.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Trong một cuộc thi có 60 câu hỏi, mỗi câu trả lời đúng được 1/6 điểm, mỗi câu trả lời sai trừ 1/2 điểm. Một bạn học sinh được tổng điểm là 8. Hỏi học sinh đó trả lời đúng mấy câu?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 10.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Có 22 ô tô gồm 3 loại: loại 4 bánh chở được 6 tấn, loại 6 bánh chở được 8 tấn, loại 8 bánh chở được 8 tấn. Số xe đó có tất cả 126 bánh và có thể chở cùng một lúc được 158 tấn. Hỏi mỗi loại có bao nhiêu xe?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 11.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Lớp 5A có 5 tổ trồng cây, số người mỗi tổ đều bằng nhau. Mỗi bạn trồng được 4 hoặc 6 cây. Cả lớp trồng được tất cả 220 cây. Hỏi có bao nhiêu bạn trồng được 4 cây? Bao nhiêu bạn trồng được 6 cây? Biết số học sinh ít hơn 50, nhiều hơn 40.</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><span class="fontstyle0" style="box-sizing: border-box;"><strong style="box-sizing: border-box;">Bài 12.</strong> </span><span class="fontstyle2" style="box-sizing: border-box;">Có 1920 quả cam, quýt và chanh được đựng trong 15 sọt. Biết mỗi sọt cam đựng 75 quả, mỗi sọt quýt đựng 180 quả và mỗi sọt chanh đựng 150 quả, và số sọt cam nhiều gấp rưỡi số sọt quýt. Hỏi mỗi loại có bao nhiêu quả?</span></p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 13.</strong> Có hai vòi bơm nước chảy vào bể có sức chứa 1230l. Vòi thứ nhất bơm được 80l trong một phút, vòi thứ hai bơm được 50 lít trong một phút. Người cho vòi thứ nhất bơm một số phút thì dừng lại để cho vòi thứ hai bơm tiếp cho đầy bể, tổng số thời gian bơm của vòi thứ nhất và vòi thứ hai là 21 phút. Hỏi mỗi vòi nước bơm trong bao nhiêu phút?</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 14.</strong> Một đội công nhân sử dụng tất cả 28 ống nước loại ống 8m và 5m để lắp đoạn ống dài 188m. Hỏi có bao nhiêu ống (nguyên) mỗi loại để lắp đủ đoạn đường ống đó?</p><p style="background-color: #fbfbfb; border: none; box-sizing: border-box; color: #6e6d76; font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; font-size: 16px; line-height: inherit; margin-bottom: var(--content-spacing); margin-left: var(--default-editor, auto); margin-right: var(--default-editor, auto); margin-top: 0px; max-width: var(--default-editor, var(--block-max-width)); padding: 0px; width: var(--default-editor, var(--block-width));"><strong style="box-sizing: border-box;">Bài 15.</strong> Một ô tô đi với vận tốc 70km/giờ đi từ tỉnh A đến tỉnh B có độ dài 300km. Ô tô đi một số giờ thì dừng lại và một xe máy đi với vận tốc 40km/giờ ngược chiều từ B đến A. Biết rằng tổng số thời gian của đi của cả ô tô và xe máy là 6 giờ. Tính thời gian đi của mỗi loại xe.</p></div><p><br /></p>

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