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

[EX Q]: Sentence: 'two men are playing a video game as another sits watching'. Find frequency of the letter 'a'
[EX A]: 7

[EX Q]: Sentence: 'a construction sign is displayed on a street'. Find frequency of the letter 'i'
[EX A]: 4

[EX Q]: Sentence: 'a very pretty and shiny clock on the wall'. Find frequency of the letter 'l'
[EX A]:
3