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

Sentence: 'a crowd of fans watch soccer players from stadium seating'. Find frequency of the letter 'f'
3

Sentence: 'a bunch of broken down trains sit in a yard'. Find frequency of the letter 'n'
5

Sentence: 'a small boy standing in front of a silver tv'. Find frequency of the letter 'v'

2