You are given a math word problem and you are supposed to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the following question and then only report the final numerical answer.
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Question: Nancy picked 12 carrots from her garden . If she threw out 2 of them and then picked 21 more the next day , how many carrots would she have total ?

Answer: 31

Question: Bobby has 142 books . Kristi has 78 books . How many more books does Bobby have than Kristi ?

Answer: 64

Question: Debby had 30 coloring books . If she gave away 7 of them , but then bought 35 more , how many would she have total ?

Answer:
58