A wire is 5 meters long, (3/5) is used up, how many meters are left
一根电线长5米，用去了(3/5)，还有多少米
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">5 * (2/5)</gadget>
<output>2</output>

<result>2</result>