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

[Q]: Sentence: 'a man on a skateboard going down a ramp while people are watching'. Find frequency of the letter 'w'
[A]: 3

[Q]: Sentence: 'two bears swim in a blue pool of water'. Find frequency of the letter 'o'
[A]: 4

[Q]: Sentence: 'a stop sign on the side of the road'. Find frequency of the letter 't'
[A]:
3