TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a bed with a mattress that has nothing on it'. Find frequency of the letter 'a'

SOLUTION: 5

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

SOLUTION: 2

PROBLEM: Sentence: 'a stop sign a street some trees grass and buildings'. Find frequency of the letter 't'

SOLUTION:
4