TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'two men sitting quietly on a park bench'. Find frequency of the letter 'a'

SOLUTION: 2

PROBLEM: Sentence: 'a man is water skiing on a river'. Find frequency of the letter 'r'

SOLUTION: 3

PROBLEM: Sentence: 'there is a red framed window inside a bathroom'. Find frequency of the letter 'i'

SOLUTION:
4