A cup of coffee, drank (2/5), how much coffee is left in the cup?
一杯咖啡，喝了(2/5)，杯中的咖啡还有几分之几？
<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>

<result>3/5 = around 0.6</result>