TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a very big nice looking living room with nice furnishings'. Find frequency of the letter 'e'

SOLUTION: 3

PROBLEM: Sentence: 'a group of people standing on grass with a train in the background'. Find frequency of the letter 'n'

SOLUTION: 6

PROBLEM: Sentence: 'three yellow plates with birds painted on'. Find frequency of the letter 'p'

SOLUTION:
2