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

[Q]: Sentence: 'a person is holding a chocolate doughnut with rainbow sprinkles'. Find frequency of the letter 's'
[A]: 4


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