The number A is 20% of the number B, and the number B is the number A.
甲数是乙数的20%，乙数是甲数的多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<result>5</result>