A glass of milk, drank (5/7), how much is left in the glass
一杯牛奶，喝了(5/7)，杯中还有多少
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>