TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'some food on plates next to each other on a table'. Find frequency of the letter 'e'

SOLUTION: 6

PROBLEM: Sentence: 'a little dog on a table while a dog groomer cuts its fur'. Find frequency of the letter 'r'

SOLUTION: 3

PROBLEM: Sentence: 'a crowd of pedestrians walking around a city'. Find frequency of the letter 'n'

SOLUTION:
3