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

Sentence: 'a person trying to flip a skateboard in a garage'. Find frequency of the letter 'a'
7

Sentence: 'some sheep are standing in a grassy field'. Find frequency of the letter 'n'
3

Sentence: 'homemade bird feeder made of a plastic bottle'. Find frequency of the letter 'b'

2