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

[Q]: Sentence: 'there is a sandwich with a lot of meat cut in half'. Find frequency of the letter 'a'
[A]: 5

[Q]: Sentence: 'a girl that has a kite in the air'. Find frequency of the letter 'r'
[A]: 2

[Q]: Sentence: 'a child who is riding on top of a skateboard'. Find frequency of the letter 'o'
[A]:
5