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

Sentence: 'a person on a surfboard in the surf of a wave'. Find frequency of the letter 's'
3

Sentence: 'different sets of luggage in a baggage claim area'. Find frequency of the letter 'r'
2

Sentence: 'a couple of kids are playing video games at home'. Find frequency of the letter 'e'

5