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

Sentence: 'a woman is taking a sip of a drink from a glass'. Find frequency of the letter 'i'
4

Sentence: 'a white bathroom sink sitting next to a toilet'. Find frequency of the letter 'i'
5

Sentence: 'a man in tan shirt holding a frisbee in grassy field'. Find frequency of the letter 'n'

5