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

Sentence: 'a man playing baseball on a television set'. Find frequency of the letter 'l'
4

Sentence: 'a variety of a different type of vegetables'. Find frequency of the letter 't'
4

Sentence: 'a wedding cake with pink roses on a silver plate'. Find frequency of the letter 'a'

4