A pile of coal is 20 tons, and (1/5) of it is used every day, how many tons are used in three days.
一堆煤20吨，每天用去它的(1/5)，三天一共用去多少吨．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">20 * (1/5) * 3</gadget>
<output>12</output>

<result>12</result>