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

[Q]: Sentence: 'salad and vegetables with me on top of plate'. Find frequency of the letter 'o'
[A]: 3

[Q]: Sentence: 'a man on stiltz is standing under a pink umbrella'. Find frequency of the letter 's'
[A]: 3

[Q]: Sentence: 'a bunch of teenagers in a classroom with laptops and books'. Find frequency of the letter 'a'
[A]:
6