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

[EX Q]: Sentence: 'some cubbies with towels in a blue bathroom'. Find frequency of the letter 'l'
[EX A]: 2

[EX Q]: Sentence: 'a picture of a toilet and toilet paper in a bathroom'. Find frequency of the letter 'o'
[EX A]: 5

[EX Q]: Sentence: 'man on a snowboard snowboarding down a snowy slope'. Find frequency of the letter 'n'
[EX A]:
7