TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'two people are riding on canoes down a river'. Find frequency of the letter 'e'

SOLUTION: 5

PROBLEM: Sentence: 'a line of people on motorcycles on the road'. Find frequency of the letter 'e'

SOLUTION: 5

PROBLEM: Sentence: 'three zebras standing near each other behind a fenced in area'. Find frequency of the letter 'r'

SOLUTION:
5