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 white toilet sitting next to a bathroom sink'. Find frequency of the letter 'b'
1

Sentence: 'black and white of man dozing on bench with cat'. Find frequency of the letter 'i'
3