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

Sentence: 'a street at night with trees and streetlights on'. Find frequency of the letter 't'
9

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

Sentence: 'the woman with glasses is holding a teddy bear'. Find frequency of the letter 'd'

3