A bundle of wires is 300 meters long, 20% of it is used up, how many meters are left?
一捆电线长300米，用去它的20%，还剩下多少米？
<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">300 * (4/5)</gadget>
<output>240</output>

<result>240</result>