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

[Q]: Sentence: 'a stop sign next to houses with christmas lights'. Find frequency of the letter 's'
[A]: 7


[Q]: Sentence: 'a chair and umbrella on a sandy beach'. Find frequency of the letter 's'
[A]: 1


[Q]: Sentence: 'a variety of vehicles travel along the road'. Find frequency of the letter 'l'
[A]:
3