Xiaobing bought a copy of "The Adventures of Hank the Police Dog" and read it in two days. He read 40% of the whole book on the first day, and 20 more pages (1/2) of the whole book on the second day. How many pages does this book have?
小兵买了一本《警犬汉克历险记》，分两天看完，第一天看了全书的40%，第二天看了全书的(1/2)还多20页．算一算，这本书一共有多少页？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

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

<gadget id="calculator">(3/5) - (1/2)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">20 / (1/10)</gadget>
<output>200</output>

<result>200</result>