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

Sentence: 'party cakes in plastic containers, with a cake with a plastic santa claus and reindeer on top'. Find frequency of the letter 's'
6

Sentence: 'a couple of buildings that has a bus out front'. Find frequency of the letter 'a'
4

Sentence: 'a big red bus is traveling down the road'. Find frequency of the letter 'd'

3