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

Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'
2

Sentence: 'a woman walking with a child that is in a wheelchair'. Find frequency of the letter 'k'
1

Sentence: 'there is a sandwich with a lot of meat cut in half'. Find frequency of the letter 'a'

5