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

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

[EX Q]: Sentence: 'a man standing on a surf board in the ocean'. Find frequency of the letter 'f'
[EX A]: 1

[EX Q]: Sentence: 'a street sign has been knocked on to the ground'. Find frequency of the letter 'g'
[EX A]:
2