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

[Q]: Sentence: 'a double-decker bus covered in children's illustrations driving next to a van'. Find frequency of the letter 'a'
[A]: 4

[Q]: Sentence: 'a dog on a couch near many pillows'. Find frequency of the letter 'p'
[A]: 1

[Q]: Sentence: 'a table full of empty wine glasses and silverware'. Find frequency of the letter 'a'
[A]:
5