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

[EX Q]: Sentence: 'a stuffed animal sitting on an empty bed'. Find frequency of the letter 'u'
[EX A]: 1

[EX Q]: Sentence: 'a bunch of broken down trains sit in a yard'. Find frequency of the letter 'n'
[EX A]: 5

[EX Q]: Sentence: 'a blurry photograph of a family with tennis gear crossing a city street'. Find frequency of the letter 'o'
[EX A]:
4