A rope is 40 meters long, and 25 meters have been used, which is equivalent to the remaining amount.
一根绳子长40米，已经用了25米，用去的相当于剩下的多少．
<gadget id="calculator">40 - 25</gadget>
<output>15</output>

<gadget id="calculator">25 / 15</gadget>
<output>5/3 = around 1.666667</output>

<result>5/3 = around 1.666667</result>