TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a jet that is flying in the sky with a banner behind it'. Find frequency of the letter 'r'

SOLUTION: 1

PROBLEM: Sentence: 'a train is sitting at a train station'. Find frequency of the letter 'r'

SOLUTION: 2

PROBLEM: Sentence: 'three elephants standing in a forest of trees and dirt'. Find frequency of the letter 's'

SOLUTION:
4