TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a bird is standing on the ledge of the building'. Find frequency of the letter 't'

SOLUTION: 3

PROBLEM: Sentence: 'a bird in a tree looking up at branches'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'a pair of chairs shaded by a large orange umbrella on a sunny beach'. Find frequency of the letter 'r'

SOLUTION:
5