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: 'a person on a skateboard going down a ramp'. Find frequency of the letter 'n'
4

Sentence: 'the woman is walking in the snow wearing skis and a ski pole'. Find frequency of the letter 'w'

4