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

[Q]: Sentence: 'three men are in a kitchen cooking and cutting through a dish'. Find frequency of the letter 'a'
[A]: 4

[Q]: Sentence: 'two people under an umbrella while walking down a sidewalk'. Find frequency of the letter 'i'
[A]: 3

[Q]: Sentence: 'guy pokes through the wall recording the baseball game as a outfielder goes for the ball'. Find frequency of the letter 'l'
[A]:
7