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

[Q]: Sentence: 'a tv in a glass mirror in the bathroom'. Find frequency of the letter 'h'
[A]: 2

[Q]: Sentence: 'a young woman dressed in green and black operating a remote control'. Find frequency of the letter 'r'
[A]: 5

[Q]: Sentence: 'sign explaining street and landscape improvements on a tree-lined street'. Find frequency of the letter 'd'
[A]:
3