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

[EX Q]: Sentence: 'a social occasion of people are uncovered before the open day'. Find frequency of the letter 'c'
[EX A]: 4

[EX Q]: Sentence: 'there is a zebra that is walking enar a car'. Find frequency of the letter 'r'
[EX A]: 4

[EX Q]: Sentence: 'a man on a surf board does a trick in the air'. Find frequency of the letter 'b'
[EX A]:
1