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

[EX Q]: Sentence: 'silhouette of person playing frisbee with moutain and sunset'. Find frequency of the letter 'i'
[EX A]: 5

[EX Q]: Sentence: 'small airplane in the process of taking off'. Find frequency of the letter 'e'
[EX A]: 3

[EX Q]: Sentence: 'a television set a laptop books a monitor and a lamp'. Find frequency of the letter 'a'
[EX A]:
7