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

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

Sentence: 'a young boy bouncing a tennis ball on a tennis racquet'. Find frequency of the letter 'a'
5

Sentence: 'the bus is parked on the side of the street'. Find frequency of the letter 'p'
1