TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'three elephants walk up a dirt trail from the water'. Find frequency of the letter 'l'

SOLUTION: 3

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

SOLUTION: 2

PROBLEM: Sentence: 'two queen size beds in a white room with white sheets'. Find frequency of the letter 't'

SOLUTION:
5