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

[EX Q]: Sentence: 'a surfer wipes out on a huge wave'. Find frequency of the letter 'a'
[EX A]: 3

[EX Q]: Sentence: 'a girl sits on a surfboard and smiles'. Find frequency of the letter 'i'
[EX A]: 3

[EX Q]: Sentence: 'a group of bikers riding down the road together'. Find frequency of the letter 'e'
[EX A]:
4