Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.
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Question: harry hound had a terrible earache yesterday . when i peered into his ears yesterday i found 36 frisky fleas having a party in his right ear and 85 baby fleas sleeping peacefully in his left ear . i cleaned out harry hound 's ears . how many fleas perished ?

Answer: 121

Question: there are some children at a bakery . as they were deciding what to buy 24 girls came in and 31 boys left . if there are 78 children in the bakery in the end how many children were there at first ?

Answer: 85

Question: katie had 9 math problems for homework . if she finished 5 of them on the bus ride home how many more did she have to do ?

Answer:
4