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

[EX Q]: Sentence: 'a half eaten doughnut in a persons hand'. Find frequency of the letter 'h'
[EX A]: 3

[EX Q]: Sentence: 'man in red shirt with black suitcase standing outside of building'. Find frequency of the letter 'i'
[EX A]: 8

[EX Q]: Sentence: 'a guy holding on to a tennis racket'. Find frequency of the letter 'o'
[EX A]:
3