TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a man playing baseball on a television set'. Find frequency of the letter 'l'

SOLUTION: 4

PROBLEM: Sentence: 'an elephant with broken tusks stands in front of a hill and boulders'. Find frequency of the letter 'n'

SOLUTION: 7

PROBLEM: Sentence: 'some giraffes moving across a big grass field'. Find frequency of the letter 'e'

SOLUTION:
3