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

Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'
7

Sentence: 'a man is taking a picture of a man and woman'. Find frequency of the letter 'a'
8

Sentence: 'a surfer on a surfboard riding the waves'. Find frequency of the letter 'r'

5

