Obviously read a 200-page book, but read 20% of the whole book in 5 days. According to this calculation, how many days will it take to finish reading the book?
明明看一本200页的书，5天看了全书的20%．照这样计算，看完全书还要几天？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 5</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">1 / (1/25)</gadget>
<output>25</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<result>20</result>