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

Sentence: 'a boy catching a frisbee while standing ins bunch of leaves'. Find frequency of the letter 'a'
5

Sentence: 'a number of small boats on a beach near an umbrella'. Find frequency of the letter 's'
2

Sentence: 'a sign for a village in scotland with a bicycle in front of it'. Find frequency of the letter 'n'

5