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

[EX Q]: Sentence: 'three young children playing with a ball in front of a huge bridge'. Find frequency of the letter 'e'
[EX A]: 5

[EX Q]: Sentence: 'people seated on a table looking very happy'. Find frequency of the letter 'g'
[EX A]: 1

[EX Q]: Sentence: 'a parking meter stands on the sidewalk beside an empty street'. Find frequency of the letter 'e'
[EX A]:
9