TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a man flying through the air on top of a skateboard'. Find frequency of the letter 'r'

SOLUTION: 3

PROBLEM: Sentence: 'a person is riding in a cart pulled by a horse'. Find frequency of the letter 'a'

SOLUTION: 4

PROBLEM: Sentence: 'a man in a suit makes the first slice into a cake'. Find frequency of the letter 't'

SOLUTION:
4