book, naughty read it (1/5) on the first day, and read 20 pages on the second day. At this time, the ratio of the number of pages read to the number of unread pages is 8:7. How many pages does this book have.
一本书，淘气第一天读了它的(1/5)，第二天读了20页，这时已读的与未读的页数比是8：7，这本书有多少页．
<gadget id="calculator">8 + 7</gadget>
<output>15</output>

<gadget id="calculator">8 / 15</gadget>
<output>8/15 = around 0.533333</output>

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

<gadget id="calculator">(8/15) - (1/5)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">20 / (1/3)</gadget>
<output>60</output>

<result>60</result>