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

[Q]: Sentence: 'town clocks affixed to a tall, brick building'. Find frequency of the letter 'r'
[A]: 1


[Q]: Sentence: 'a red train traveling down train tracks near a forest'. Find frequency of the letter 'f'
[A]: 1


[Q]: Sentence: 'two zebras are standing on a grassy area'. Find frequency of the letter 'r'
[A]:
4