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

Sentence: 'a man with headphones on is hunched over a sink while being recorded'. Find frequency of the letter 'd'
4

Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'
4

Sentence: 'a little boy reading a book with the covers over his body'. Find frequency of the letter 't'

4