There are 9 tons of coal in the school cafeteria, and 3000 kilograms are used. How many tons are left?
学校食堂有9吨煤，用了3000千克，还剩多少吨．
<gadget id="calculator">3_000 / 1_000</gadget>
<output>3</output>

<gadget id="calculator">9 - 3</gadget>
<output>6</output>

<result>6</result>