There are two ropes, the first one is 40 meters long and 20% shorter than the second one, how long is the second one?
有两根绳子，第一根长40米，比第二根短20%，第二根绳子有多长？
<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">40 / (4/5)</gadget>
<output>50</output>

<result>50</result>