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

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

Sentence: 'a few giraffes standing in a field looking around'. Find frequency of the letter 'e'
3

Sentence: 'a person jumping up into the air on a skateboard'. Find frequency of the letter 't'
3