Obviously reading a storybook, I read 35% of the whole book on the first day, and 30 pages on the second day, and just half of it was not read, how many pages in the whole book?
明明读一本故事书，第一天读了全书的35%，第二天读了30页，刚好还有一半没有读，全书多少页？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">(1/2) - (7/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">30 / (3/20)</gadget>
<output>200</output>

<result>200</result>