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

Sentence: 'a couple of buses parked on the side of the street'. Find frequency of the letter 'b'
1

Sentence: 'girls posing of a picture one holding a tennis racket the other wearing a crown'. Find frequency of the letter 'g'
4

Sentence: 'a man in a vest and tie leaning against a wall'. Find frequency of the letter 'a'

9