Xiao Ming reads a storybook. He reads 20 pages on the first day, 25 pages on the second day, and leaves 40% of the book unread. How many pages does this storybook have?
小明读一本故事书，第一天读了20页，第二天读了25页，还余下全书的40%没有读，这本故事书共有多少页？
<gadget id="calculator">20 + 25</gadget>
<output>45</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">45 / (3/5)</gadget>
<output>75</output>

<result>75</result>