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

Sentence: 'men are riding on motorcycles with a man riding in their carriers'. Find frequency of the letter 'r'
8

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

Sentence: 'two baked pizzas on some wooden cutting boards'. Find frequency of the letter 'c'

1