If you read 20% of the book on the first day, read 11 pages on the second day, and left 25% unread, how many pages are there in total?
一本书，第一天读了全书的20%，第二天读了11页，还剩25%没有读，则这本一共多少页？
<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 - (1/5) - (1/4)</gadget>
<output>11/20 = around 0.55</output>

<gadget id="calculator">11 / (11/20)</gadget>
<output>20</output>

<result>20</result>