TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a man sitting in front of a laptop computer next to a child'. Find frequency of the letter 'e'

SOLUTION: 2

PROBLEM: Sentence: 'a big bear walks through some grass'. Find frequency of the letter 'a'

SOLUTION: 4

PROBLEM: Sentence: 'two elephants in a sandy pen next to a fence'. Find frequency of the letter 'w'

SOLUTION:
1