The school canteen shipped 870 tons of rice, 320 tons were used last month, and 370 tons were used this month. How many tons of rice are left?
学校食堂运来大米870吨，上个月用去320吨，这个月用去370吨，还剩多少吨大米？
<gadget id="calculator">870 - 320 - 370</gadget>
<output>180</output>

<result>180</result>