TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a girl sits on a surfboard and smiles'. Find frequency of the letter 'i'

SOLUTION: 3

PROBLEM: Sentence: 'a bunch of cows that are in the field'. Find frequency of the letter 'a'

SOLUTION: 3

PROBLEM: Sentence: 'an image of a man and his kids in front of a birthday cake'. Find frequency of the letter 'n'

SOLUTION:
5