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: 'large grassy pasture filled with trees and a single horse'. Find frequency of the letter 'l'

SOLUTION: 4

PROBLEM: Sentence: 'the group of motorcyclist are parked on the side of the road'. Find frequency of the letter 'o'

SOLUTION:
7