There are 9 tons of coal in the school cafeteria, 5000kg is used, how many tons are left?
学校食堂有9吨煤，用了5000kg，还剩多少吨．
<gadget id="calculator">5_000 / 1_000</gadget>
<output>5</output>

<gadget id="calculator">9 - 5</gadget>
<output>4</output>

<result>4</result>