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

Sentence: 'a grey hummingbird by fence and tree branches'. Find frequency of the letter 'y'
2

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

Sentence: 'a dog lying on the floor wearing a santa hat'. Find frequency of the letter 'i'

2