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 playing baseball on a television set'. Find frequency of the letter 'l'

Answer: 4

Question: Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'

Answer: 3

Question: Sentence: 'a plate of food, with broccoli and nuts'. Find frequency of the letter 'b'

Answer:
1