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

Sentence: 'a chair and umbrella on a sandy beach'. Find frequency of the letter 's'
1

Sentence: 'a person holding onto a pink kite at the beach'. Find frequency of the letter 'n'
4

Sentence: 'a large poster hangs overhead above large wooden crates'. Find frequency of the letter 'a'

7