A pile of coal, transported away (6/7), how much of this pile of coal is left
一堆煤，运走(6/7)，还剩下这堆煤的多少
<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">1 - (6/7)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>