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 skating down a stair rail in front of a bunch of people'. Find frequency of the letter 'o'

SOLUTION: 5

PROBLEM: Sentence: 'a couple of buses parked on the side of the street'. Find frequency of the letter 'b'

SOLUTION: 1

PROBLEM: Sentence: 'people gathered under umbrellas with street vendors on a sunny day'. Find frequency of the letter 'a'

SOLUTION:
4