TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'an audience watches as a bird spreads its wings'. Find frequency of the letter 'd'

SOLUTION: 3

PROBLEM: Sentence: 'a flock of sheep grazing in a park'. Find frequency of the letter 'f'

SOLUTION: 2

PROBLEM: Sentence: 'a professional tennis player holding a tennis racket at the us open'. Find frequency of the letter 'o'

SOLUTION:
4