A rope is 5 meters long, how many meters are left after (2/5) of it is used up?
一根绳子长5米，用去它的(2/5)后，还剩多少米．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5 * (3/5)</gadget>
<output>3</output>

<result>3</result>