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

Sentence: 'a person is water skiing and there are birds flying around above them'. Find frequency of the letter 'n'
5

Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'
4

Sentence: 'a baby is sitting and holding a teddy bear'. Find frequency of the letter 'd'

4