A pile of coal weighs 10 tons, and if (1/5) ton is used up every day, how many days can it be used up?
一堆煤重10吨，每天用去(1/5)吨，多少天可以用完．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 / (1/5)</gadget>
<output>50</output>

<result>50</result>