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

[EX Q]: Sentence: 'oranges are sitting in a bowl on a table'. Find frequency of the letter 'a'
[EX A]: 5

[EX Q]: Sentence: 'a couple of buildings that has a bus out front'. Find frequency of the letter 'a'
[EX A]: 4

[EX Q]: Sentence: 'a man waling through a train rail yard with trains passing on either side of him'. Find frequency of the letter 'r'
[EX A]:
6