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

[Q]: Sentence: 'several zebras  and a giraffe in an enclosure'. Find frequency of the letter 's'
[A]: 3


[Q]: Sentence: 'a chair and umbrella on a sandy beach'. Find frequency of the letter 's'
[A]: 1


[Q]: Sentence: 'a bird eats an apple off of a tree'. Find frequency of the letter 'r'
[A]:
2