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

Sentence: 'a small wrinkley dog wearing a bow tie'. Find frequency of the letter 'e'
3

Sentence: 'a traffic signal by a wire filled with some birds'. Find frequency of the letter 'e'
3

Sentence: 'a man riding a wave on top of a surfboard'. Find frequency of the letter 'a'

6