In this task, you need to count the number of times the given letter appears in the given sentence.
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Question: Sentence: 'a couple of buildings that has a bus out front'. Find frequency of the letter 'a'

Answer: 4

Question: Sentence: 'a small dog sits in the rear window of a car'. Find frequency of the letter 'm'

Answer: 1

Question: Sentence: 'a person on a surfboard on rapids in a river'. Find frequency of the letter 'd'

Answer:
2