A canteen used 256 tons of water in the first half of last year and 224 tons in the second half of the year. How many tons of water is used on average per month? What is the column
某食堂去年上半年用水256吨，下半年用水224吨．平均每月用水多少吨？列式是多少
<gadget id="calculator">256 + 224</gadget>
<output>480</output>

<gadget id="calculator">480 / 12</gadget>
<output>40</output>

<result>40</result>