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 car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'

Answer: 2

Question: Sentence: 'a man with a skateboard that is in the street'. Find frequency of the letter 'o'

Answer: 1

Question: Sentence: 'a biplane flying low over a planted field'. Find frequency of the letter 'w'

Answer:
1