Obviously, I have read 60 pages of a storybook, accounting for 20% of the whole book, how many pages are left?
明明看一本故事书已经看了60页，占全书的20%，还有多少页没有看？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">60 / (1/5)</gadget>
<output>300</output>

<gadget id="calculator">300 - 60</gadget>
<output>240</output>

<result>240</result>