A rope is (4/5) meters long, how many meters are left after (4/5) of it is used up?
一根绳长(4/5)米，用去它的(4/5)后，还剩多少米．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(4/5) * (1/5)</gadget>
<output>4/25 = around 0.16</output>

<result>4/25 = around 0.16</result>