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

Sentence: 'two people are riding on canoes down a river'. Find frequency of the letter 'e'
5

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

Sentence: 'a dog in some grass looking at its reflections'. Find frequency of the letter 'o'

5