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 line of people on motorcycles on the road'. Find frequency of the letter 'e'

SOLUTION: 5

PROBLEM: Sentence: 'an outdoor over is pictured in a back yard'. Find frequency of the letter 'a'

SOLUTION:
4