TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a red and white train passing a train station'. Find frequency of the letter 'a'

SOLUTION: 7

PROBLEM: Sentence: 'the small black and white dog holds onto a frisbee'. Find frequency of the letter 'h'

SOLUTION: 3

PROBLEM: Sentence: 'a baby sitting on a table beside a microwave'. Find frequency of the letter 'o'

SOLUTION:
2