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

[Q]: Sentence: 'a plastic plastic plate topped with three different type of food'. Find frequency of the letter 'l'
[A]: 3


[Q]: Sentence: 'a man riding on the back of a white horse next to other horses'. Find frequency of the letter 'o'
[A]: 6


[Q]: Sentence: 'a lonely bike leaning up against the side of a building'. Find frequency of the letter 'n'
[A]:
5