2 tons of coal have been transported away, and there are 5 tons left, how much of the coal has been transported
一堆煤运走了2吨，还剩下5吨，运走了这堆煤的多少
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<result>2/7 = around 0.285714</result>