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 line of people on motorcycles on the road'. Find frequency of the letter 'e'

Answer: 5


Question: Sentence: 'a red and white train passing a train station'. Find frequency of the letter 'a'

Answer: 7


Question: Sentence: 'a young man snow boarding on a fence rail'. Find frequency of the letter 'n'

Answer:
6