TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a double decker bus with a lot of people on board'. Find frequency of the letter 'l'

SOLUTION: 3

PROBLEM: Sentence: 'a woman standing in front of a bathroom sink in front of a mirror'. Find frequency of the letter 'o'

SOLUTION: 8

PROBLEM: Sentence: 'a red and a black laptop on a round black table near two people sitting down'. Find frequency of the letter 'n'

SOLUTION:
6