For a 5-meter-long rope, after cutting (1/5) of the full length, there is still the original rope length ((())/(())), how many meters are left.
5米长的绳子，剪去全长的(1/5)后还剩下原绳子长的((())/(()))，还剩多少米．
<gadget id="calculator">1 / 5</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">5 * (4/5)</gadget>
<output>4</output>

<result>4</result>