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

[EX Q]: Sentence: 'a man is taking a picture of a man and woman'. Find frequency of the letter 'a'
[EX A]: 8

[EX Q]: Sentence: 'there is a person standing on a blue towel'. Find frequency of the letter 'n'
[EX A]: 4

[EX Q]: Sentence: 'a man riding a bucking bronco in a rodeo'. Find frequency of the letter 'r'
[EX A]:
3