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

[EX Q]: Sentence: 'a small dog sits in the rear window of a car'. Find frequency of the letter 'm'
[EX A]: 1

[EX Q]: Sentence: 'the sun goes down over a bike tied to a bench at the beach'. Find frequency of the letter 't'
[EX A]: 5

[EX Q]: Sentence: 'a young man on a skateboard  jumping a skateboard ramp'. Find frequency of the letter 'o'
[EX A]:
4