TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a yellow fire hydrant in the forefront of a roadway'. Find frequency of the letter 'r'

SOLUTION: 5

PROBLEM: Sentence: 'pedestrians pass by a stop sign, some holding surfboards'. Find frequency of the letter 'n'

SOLUTION: 3

PROBLEM: Sentence: 'a cake is lit with tall yellow candles'. Find frequency of the letter 't'

SOLUTION:
3