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

[Q]: Sentence: 'a couple of boys in a field playing baseball'. Find frequency of the letter 'i'
[A]: 3

[Q]: Sentence: 'a man with a large grey and black beard and glasses and a tie'. Find frequency of the letter 'e'
[A]: 5

[Q]: Sentence: 'the large crowd came to watch the baseball game'. Find frequency of the letter 'g'
[A]:
2