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

[Q]: Sentence: 'a woman and a child walking down a street with a kite'. Find frequency of the letter 'n'
[A]: 4

[Q]: Sentence: 'three young children playing with a ball in front of a huge bridge'. Find frequency of the letter 'e'
[A]: 5

[Q]: Sentence: 'a cat standing above a pair of brown shoes'. Find frequency of the letter 'b'
[A]:
2