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

[Q]: Sentence: 'a table topped with a cupcake on a picture of a cupcake'. Find frequency of the letter 'o'
[A]: 3


[Q]: Sentence: 'a blue train on a track next to another track'. Find frequency of the letter 'c'
[A]: 2


[Q]: Sentence: 'i cannot tell if those are plantains or unripe bananas'. Find frequency of the letter 'a'
[A]:
7