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

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

Sentence: 'a small boy in a high chair eating a cupcake'. Find frequency of the letter 'i'
4

Sentence: 'outside of a tennis court are a man kneeling down while another man is in a seat sitting up high and a tennis player in blue is having their foot wrapped'. Find frequency of the letter 'n'

15