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

Sentence: 'a grapefruit, toast, coffee and other items are on a tray'. Find frequency of the letter 't'
6

Sentence: 'a man paddle boarding by a boat dock in a city'. Find frequency of the letter 'o'
3

Sentence: 'woman in a blue dress serving on a tennis court'. Find frequency of the letter 'e'
4