How many meters are left after cutting (1/5) of 10 meters of wire.
10米的铁丝截去(1/5)后还剩多少米．
<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">10 * (4/5)</gadget>
<output>8</output>

<result>8</result>