Reading a book, I read 20% of the whole book on the first day, and 25% of the whole book on the second day. I read exactly 108 pages in two days. How many pages does this book have?
看一本书，第一天看了全书的20%，第二天看了全书的25%，两天正好看了108页，这本书共有多少页？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) + (1/4)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">108 / (9/20)</gadget>
<output>240</output>

<result>240</result>