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

[EX Q]: Sentence: 'a little dog on a table while a dog groomer cuts its fur'. Find frequency of the letter 'r'
[EX A]: 3

[EX Q]: Sentence: 'man in air skateboarding on street with building'. Find frequency of the letter 't'
[EX A]: 4

[EX Q]: Sentence: 'a person jumping up into the air on a skateboard'. Find frequency of the letter 't'
[EX A]:
3