TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'girls posing of a picture one holding a tennis racket the other wearing a crown'. Find frequency of the letter 'g'

SOLUTION: 4

PROBLEM: Sentence: 'a person standing operating a cell phone in a room'. Find frequency of the letter 'n'

SOLUTION: 6

PROBLEM: Sentence: 'the girl is sitting in one of two identical chairs in front of a television'. Find frequency of the letter 'i'

SOLUTION:
11