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

Q: Sentence: 'a small white dog looking out a car window'. Find frequency of the letter 'l'

A: 3
****
Q: Sentence: 'three birds are sitting on a tree in a forest'. Find frequency of the letter 'h'

A: 1
****
Q: Sentence: 'a desk with two monitors and a keyboard'. Find frequency of the letter 'd'

A:
3
****
