A newly opened store sells a mop, 280 pieces are sold in the morning and 550 pieces are sold in the afternoon. How many more were sold in the afternoon than in the morning?
新开商店卖一种拖布，上午卖出280件，下午卖出550件．下午比上午多卖出多少件？
<gadget id="calculator">550 - 280</gadget>
<output>270</output>

<result>270</result>