TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a car accident has slowed traffic as a clean up crew works'. Find frequency of the letter 'f'

SOLUTION: 2

PROBLEM: Sentence: 'a couple of buses parked on the side of the street'. Find frequency of the letter 'b'

SOLUTION: 1

PROBLEM: Sentence: 'a old train that is on a train track'. Find frequency of the letter 'r'

SOLUTION:
3