TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'pedestrians pass by a stop sign, some holding surfboards'. Find frequency of the letter 'n'

SOLUTION: 3

PROBLEM: Sentence: 'a couple is cutting in to a cake at a wedding'. Find frequency of the letter 'd'

SOLUTION: 2

PROBLEM: Sentence: 'a plane sitting parked on the cement near grass'. Find frequency of the letter 'e'

SOLUTION:
6