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

Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'
3

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

Sentence: 'a man that is surfing on some water'. Find frequency of the letter 'm'

2