A pile of 30 tons of coal is transported away (3/5), how many tons are left?
一堆煤30吨，运走了(3/5)，还剩多少吨．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">30 * (2/5)</gadget>
<output>12</output>

<result>12</result>