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 passenger bus that is driving down the street'. Find frequency of the letter 'r'

Answer: 3


Question: Sentence: 'a bunch of cows that are in the field'. Find frequency of the letter 'a'

Answer: 3


Question: Sentence: 'a skier is down on the ground as others help'. Find frequency of the letter 'e'

Answer:
4