Hao Xue read a science and technology book. He read 60 pages on the first day, 20% of the book on the second day, and half of the book in two days. How many pages does the book have?
郝学看一本科技书，第一天看了60页，第二天看了全书的20%，两天刚好看了这本书的一半，这本书一共有多少页？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

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

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">60 / (3/10)</gadget>
<output>200</output>

<result>200</result>