Xiaohua reads a book. He reads 15% of the whole book on the first day and 20% of the whole book on the second day. He reads a total of 70 pages in two days. How many pages does this book have?
小华读一本书，第一天读了全书的15%，第二天读了全书的20%，两天共读了70页，这本书共有多少页？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/20) + (1/5)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">70 / (7/20)</gadget>
<output>200</output>

<result>200</result>