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

[Q]: Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'
[A]: 2

[Q]: Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'
[A]: 5

[Q]: Sentence: 'light shines on a clean kitchen with white appliances'. Find frequency of the letter 'p'
[A]:
2