A newly opened store sells a mop, 280 pieces are sold in the morning and 550 pieces are sold in the afternoon. How many pieces were sold in the morning and afternoon?
新开商店卖一种拖布，上午卖出280件，下午卖出550件．上午和下午一共卖出多少件？
<gadget id="calculator">280 + 550</gadget>
<output>830</output>

<result>830</result>