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

Sentence: 'a person dressed all in black snowboarding down a slope'. Find frequency of the letter 'e'
4

Sentence: 'a cat sleeping near lots of pairs of shoes'. Find frequency of the letter 'r'
2

Sentence: 'old double decker bus parked in a lot'. Find frequency of the letter 't'

1