There is a pile of coal, 3 tons are removed, and there are 4 tons left, how much of this pile of coal is removed
有一堆煤，运走3吨，还剩4吨，运走的是这堆煤的多少
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>