Xiaoying and Xiaoming read the same story book. When Xiaoying finished reading (1/4) of the book, Xiaoming still had 240 pages left; when Xiaoying finished reading the rest (4/5), Xiaoming still had (8/25) the whole book I haven't finished reading it, smart you, do you know how many pages this book has? Do the math!
小颖和小明读同样的一本故事书．当小颖读完全书的(1/4)时，小明还剩240页没有看完；当小颖又读完剩下的(4/5)时，小明还剩下全书的(8/25)没有读完，聪明的你，知道这本书有多少页吗？算算看！
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) / 5</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 4</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">240 / (4/5)</gadget>
<output>300</output>

<result>300</result>