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

Sentence: 'cooked fish and green broccoli share a single white plate'. Find frequency of the letter 'c'
3

Sentence: 'a black bear sitting in the grass taking a rest'. Find frequency of the letter 'a'
6

Sentence: 'a couple of baseball players are playing ball while a crowd looks on'. Find frequency of the letter 'e'

5