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

[Q]: Sentence: 'a bird in a tree looking up at branches'. Find frequency of the letter 'e'
[A]: 3


[Q]: Sentence: 'the large modern train is on the train track'. Find frequency of the letter 'm'
[A]: 1


[Q]: Sentence: 'a small boy chewing on a blue and white toy'. Find frequency of the letter 'b'
[A]:
2