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

[EX Q]: Sentence: 'an airplane is being towed away from the jet bridge'. Find frequency of the letter 's'
[EX A]: 1

[EX Q]: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'
[EX A]: 4

[EX Q]: Sentence: 'a pile of fresh green vegetables on top of a table'. Find frequency of the letter 'n'
[EX A]:
2