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

Sentence: 'a man sitting in front of a laptop computer next to a child'. Find frequency of the letter 'e'
2

Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'
2

Sentence: 'an office desk with antiques underneath a beautiful painting'. Find frequency of the letter 's'

2