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

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

Sentence: 'two women with clear umbrellas stand near two people in uniforms near a building with a thatched roof'. Find frequency of the letter 'w'

5