Xiao Ming reads a story book. On the first day, he reads 20% of the whole book. On the second day, he reads 1/4 of the whole book. On the second day, he reads 9 pages more than on the first day. How many pages does this book have?
小明看一本故事书，第一天看了全书的20%，第二天看了全书的(1/4)，第二天比第一天多看了9页，这本书共有多少页？
<gadget id="calculator">1 / 4</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">9 / (1/20)</gadget>
<output>180</output>

<result>180</result>