Xiaoli reads a book. She reads 20% of the whole book on the first day, 40 pages on the second day, and the remaining 15% on the third day. At this time, she can see the book after reading 2 more pages. half of the pages. How many pages does this book have in total?
小莉看一本书，第一天看了全书的20%，第二天看了40页，第三天又看了剩下的15%，这时再看2页就可以看到这本书页数的一半了．这本书一共有多少页．
<gadget id="calculator">42 - 6</gadget>
<output>36</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">3 / 25</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">(1/2) - (1/5) - (3/25)</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">36 / (9/50)</gadget>
<output>200</output>

<result>200</result>