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

[EX Q]: Sentence: 'men are riding on motorcycles with a man riding in their carriers'. Find frequency of the letter 'r'
[EX A]: 8

[EX Q]: Sentence: 'a couple of people are sitting at a table'. Find frequency of the letter 'e'
[EX A]: 5

[EX Q]: Sentence: 'a professional soccer player about to kick the ball'. Find frequency of the letter 'a'
[EX A]:
5