pile of coal has 140 tons. How many tons are left after (5/7) removes the pile of coal?
一堆煤有140吨，运走这堆煤的(5/7)，还剩下多少吨．
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">140 * (2/7)</gadget>
<output>40</output>

<result>40</result>