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

Sentence: 'two metal  benches on an empty train platform'. Find frequency of the letter 'n'
4

Sentence: 'old double decker bus parked in a lot'. Find frequency of the letter 't'
1

Sentence: 'there is a woman that is standing on top of a white fire hyrdrant'. Find frequency of the letter 'i'

5