TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'two zebras standing around while a third zebra drinks from a pond'. Find frequency of the letter 's'

SOLUTION: 3

PROBLEM: Sentence: 'a surfer is in the middle of an ocean wave'. Find frequency of the letter 'i'

SOLUTION: 3

PROBLEM: Sentence: 'a slice of pizza siting on a triangular paper plate'. Find frequency of the letter 'l'

SOLUTION:
3