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

[EX Q]: Sentence: 'a person that is looking out his window'. Find frequency of the letter 'n'
[EX A]: 3

[EX Q]: Sentence: 'a bunch of cows that are in the field'. Find frequency of the letter 'a'
[EX A]: 3

[EX Q]: Sentence: 'a group of forks going toward a cake on a plate'. Find frequency of the letter 'a'
[EX A]:
6