TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'several zebras  and a giraffe in an enclosure'. Find frequency of the letter 's'

SOLUTION: 3

PROBLEM: Sentence: 'a piece of film shows two street signs crossing each other'. Find frequency of the letter 'f'

SOLUTION: 2

PROBLEM: Sentence: 'a guy is riding a skateboard on a ramp'. Find frequency of the letter 'a'

SOLUTION:
6