After transferring 20% of the coal in pile A to pile B, the two piles have the same amount of coal, and pile B is originally pile A's ((())/(())).
将甲堆煤的20%调入乙堆后，两堆煤一样多，原来乙堆是甲堆的((())/(()))．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5) - (1/5)</gadget>
<output>3/5 = around 0.6</output>

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