Imagine a question and stream-of-consciousness explanation for which this is the answer: 35
Question: 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?
Stream-of-consciousness: The total number of green and red plates is 28 + 21 = 49. Xavier should buy 84 − 49 = 35 more plates.