In this task, you need to count the number of times the given letter appears in the given sentence.

Q: Sentence: 'a green bus driving in a street filled with heavy traffic'. Find frequency of the letter 'v'

A: 2
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Q: Sentence: 'pizza with different vegetables sitting on top of a wooden slab'. Find frequency of the letter 'o'

A: 5
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Q: Sentence: 'a small grey refrigerator on wheels and a sand fan'. Find frequency of the letter 'a'

A:
7
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