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

[EX Q]: Sentence: 'a small white dog looking out a car window'. Find frequency of the letter 'l'
[EX A]: 3

[EX Q]: Sentence: 'older man getting ready to swing his bat at a ball on a stand in front of a group of viewers'. Find frequency of the letter 'n'
[EX A]: 7

[EX Q]: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'h'
[EX A]:
3