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 man with headphones on is hunched over a sink while being recorded'. Find frequency of the letter 'd'

Answer: 4


Question: Sentence: 'a small boat and a large boat on a river near a city'. Find frequency of the letter 'a'

Answer: 10


Question: Sentence: 'a couple of men riding horses down  sidewalk'. Find frequency of the letter 'o'

Answer:
4