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

Sentence: 'a green bus driving in a street filled with heavy traffic'. Find frequency of the letter 'v'
2

Sentence: 'a parking meter painted green with a sign that describes it as not a parking meter'. Find frequency of the letter 's'
4

Sentence: 'a woman that is sitting on steps next to a dog'. Find frequency of the letter 'p'

1