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

Sentence: 'two elephants walking on cement next to wall'. Find frequency of the letter 'n'
5

Sentence: 'a couple is cutting in to a cake at a wedding'. Find frequency of the letter 'd'
2

Sentence: 'light shines on a clean kitchen with white appliances'. Find frequency of the letter 'p'

2