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

Sentence: 'a very big nice looking living room with nice furnishings'. Find frequency of the letter 'e'
3

Sentence: 'a plane with stairs next to it sitting in a large lot'. Find frequency of the letter 'i'
6

Sentence: 'a man sitting on a bench looking at his cell phone'. Find frequency of the letter 'b'
1