Li Dan read a story book, read 25% of the book on the first day, read 25 pages on the second day, just read (1/2) of this book in two days. Do you know how many pages this book has?
李丹同学看一本故事书，第一天看了这本书的25%，第二天看了25页，两天正好看了这本书的(1/2)．你知道这本书有多少页吗？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/2) - (1/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">25 / (1/4)</gadget>
<output>100</output>

<result>100</result>