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 bed with a mattress that has nothing on it'. Find frequency of the letter 'a'
5

Sentence: 'a stop sign that is attached to a pole'. Find frequency of the letter 'p'

2