For a book, Xiao Ming read 25% of the whole book on the first day and 20% of the whole book on the second day, and read 10 more pages on the first day than on the second day. How many pages does this book have?
一本书，小明第一天看了全书的25%，第二天看了全书的20%，第一天比第二天多看10页．这本书一共有多少页？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">10 / (1/20)</gadget>
<output>200</output>

<result>200</result>