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

Sentence: 'a bird is perched on a container in a person's hand'. Find frequency of the letter 'c'
2

Sentence: 'a person working at an airport, outside of an airplane'. Find frequency of the letter 'r'
5

Sentence: 'many people sitting under umbrellas on a sunny beach'. Find frequency of the letter 'n'

6