The weight ratio of two piles of coal, A and B, is 5:4, and as much as pile A is used, it will be as much as pile B.
甲、乙两堆煤重量比为5：4，甲堆用去多少后就和乙堆一样多．
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>