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

Sentence: 'bathroom scene with a black cat going behind the door'. Find frequency of the letter 'e'
4

Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'
2

Sentence: 'green vase with pink flowers sticking out of the top of it'. Find frequency of the letter 'i'

5