For a book, if you read 2 pages less than this book (1/7) on the first day, and read from page 30 on the second day, how many pages does this book have?
一本书，第一天看的比这本书的(1/7)少2页，第二天从30页看起，这本书有多少页？
<gadget id="calculator">30 - 1</gadget>
<output>29</output>

<gadget id="calculator">2 + 29</gadget>
<output>31</output>

<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">31 / (1/7)</gadget>
<output>217</output>

<result>217</result>