Xiao Ming reads a book. On the first day, he read 20 pages more than the whole book (3/20). There are 150 pages left in this book. How many pages are there in this book?
小明读一本书，第一天读了比全书的(3/20)多20页，这本书还剩下150页，这本书共几页？
<gadget id="calculator">150 + 20</gadget>
<output>170</output>

<gadget id="calculator">3 / 20</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">1 - (3/20)</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">170 / (17/20)</gadget>
<output>200</output>

<result>200</result>