Read a book mischievously, read 30% of the whole book in the first week, read 50% of the whole book in the second week, and still haven’t read 70 pages, how many pages does this book have?
淘气看一本书，第一周看了全书的30%，第二周看了全书的50%，还有70页没看，这本书共有多少页？
<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (3/10) - (1/2)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">70 / (1/5)</gadget>
<output>350</output>

<result>350</result>