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

[Q]: Sentence: 'a bunch of people are standing out in a field a red one has their arms out as a white ball is in the air'. Find frequency of the letter 'e'
[A]: 9

[Q]: Sentence: 'a photo of a couple of people at a convention'. Find frequency of the letter 'v'
[A]: 1

[Q]: Sentence: 'a few guys stand ready to play baseball'. Find frequency of the letter 'o'
[A]:
1