garment factory processes garments in the first three months: 280 sets in January, 240 sets in February, and 320 sets in March. How many sets of garments does this garment factory process per month on average.
一个服装厂第一季度三个月加工服装分别为：一月份280套、二月份240套、三月份320套．这个服装厂平均每月加工服装多少套．
<gadget id="calculator">280 + 240 + 320</gadget>
<output>840</output>

<gadget id="calculator">840 / 3</gadget>
<output>280</output>

<result>280</result>