human
Xavier needs 84 paper plates for a housewarming party. He already has 21 green plates and 28 red plates. How many more plates should Xavier buy?
assistant
How many plates does Xavier have? ** The total number of green and red plates is 28 + 21 = <<28+21=49>>49.
How many more plates should Xavier buy? ** Xavier should buy 84 − 49 = 35 more plates.
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