Take out (1/5) of the coal from pile A to pile B. At this time, the weight of the two piles of coal is equal. How many percent is the weight of coal in pile B less than the weight of coal in pile A?
从甲堆煤中，取出(1/5)给乙堆，这时两堆煤重量就相等了，原来乙堆煤的重量比甲堆煤的重量少百分之几？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">2 / 1</gadget>
<output>2</output>

<gadget id="calculator">(1/5) * 2</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>