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

[Q]: Sentence: 'three young people goofing around; one of the guys has a football, the girl has a teddy bear'. Find frequency of the letter 'd'
[A]: 3


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


[Q]: Sentence: 'a train platform with a  red bench on it'. Find frequency of the letter 'e'
[A]:
2