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

Sentence: 'a guy riding a bike close to a car in the street'. Find frequency of the letter 'i'
4

Sentence: 'a group of giraffes walk together by a hill'. Find frequency of the letter 'b'
1

Sentence: 'the snowboarder wearing a dark helmet sprays snow into the air'. Find frequency of the letter 'w'

3