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

Sentence: 'some cubbies with towels in a blue bathroom'. Find frequency of the letter 'l'
2

Sentence: 'a crowd of people standing in front of a green train'. Find frequency of the letter 'g'
2

Sentence: 'a man sits on a couch while a dog lies on the floor'. Find frequency of the letter 'e'

3