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

Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'
3

Sentence: 'a bed with a dog laying on it next to two laptop computers'. Find frequency of the letter 'n'
3

Sentence: 'a herd of sheep standing on top of a grass hillside'. Find frequency of the letter 'l'

2