The speed of the slow car is 20% slower than the speed of the fast car, how much faster is the speed of the fast car than the slow car.
慢车的速度比快车速度慢20%，快车比慢车快多少．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/5) / (4/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>