TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a small dog sits in the rear window of a car'. Find frequency of the letter 'm'

SOLUTION: 1

PROBLEM: Sentence: 'a man serving himself pizza in a wooden booth'. Find frequency of the letter 'n'

SOLUTION: 4

PROBLEM: Sentence: 'a man riding a brown horse over a jump'. Find frequency of the letter 'a'

SOLUTION:
4