If 20% of a rope is cut off, it is exactly (4/5) meters. How many meters is the original length of the rope?
一根绳子剪去它的20%，正好是(4/5)米，这根绳子原来长多少米．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<result>4</result>