TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a bus with two floors belonging to london country'. Find frequency of the letter 't'

SOLUTION: 4

PROBLEM: Sentence: 'a cat that is standing next to an open suitcase'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'a man in a red shirt throws a white frisbee'. Find frequency of the letter 'a'

SOLUTION:
4