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

Sentence: 'a couple of people are sitting at a table'. Find frequency of the letter 'e'
5

Sentence: 'young boy flying kite in large field at outdoor event'. Find frequency of the letter 'y'
3

Sentence: 'orange semi truck driving on a town roadway'. Find frequency of the letter 'a'

4