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

Sentence: 'there is a woman pointing at something with her dog'. Find frequency of the letter 'i'
5

Sentence: 'a man with a large grey and black beard and glasses and a tie'. Find frequency of the letter 'e'
5

Sentence: 'a picture of someone trying to para-sail in the ocean'. Find frequency of the letter 'r'

3