An extra-curricular book has 140 pages. The number of pages that Pingping read is exactly 3/7 of the remaining pages. How many pages are left unread? (solution with equation)
一本课外书140页，萍萍读的页数正好是剩下页数的(3/7)，还剩多少页没有读？(用方程解答)
<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(3/7) + 1</gadget>
<output>10/7 = around 1.428571</output>

<gadget id="calculator">140 / (10/7)</gadget>
<output>98</output>

<result>98</result>