TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'three birds are sitting on a tree in a forest'. Find frequency of the letter 'h'

SOLUTION: 1

PROBLEM: Sentence: 'a grey hummingbird by fence and tree branches'. Find frequency of the letter 'y'

SOLUTION: 2

PROBLEM: Sentence: 'a city street has a bus and a car'. Find frequency of the letter 's'

SOLUTION:
3