When Xiaolin reads a book, he reads (3/5) of the total pages on the first day, and 20% on the second day, leaving 20 pages left. How many pages does this book have?
小林看一本书，第一天看了总页数的(3/5)，第二天看了20%，还剩20页．这本书有多少页？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">1 - (3/5) - (1/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 / (1/5)</gadget>
<output>100</output>

<result>100</result>