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

Sentence: 'a man using a video game controller in a room'. Find frequency of the letter 'n'
4

Sentence: 'children with scissors and construction paper in a school classroom'. Find frequency of the letter 'c'
6

Sentence: 'a truck painted in camouflage sitting parked on cement'. Find frequency of the letter 'n'

5