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

[Q]: Sentence: 'a train sits on a railroad track as a metal awning covers it'. Find frequency of the letter 'l'
[A]: 2


[Q]: Sentence: 'a close up of a train on a track in the dark'. Find frequency of the letter 'a'
[A]: 6


[Q]: Sentence: 'a man with a baseball bat waits to hit the ball as another waits to catch it'. Find frequency of the letter 'b'
[A]:
4