TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a small white plane sitting on top of the ocean'. Find frequency of the letter 'e'

SOLUTION: 4

PROBLEM: Sentence: 'a young man with glasses on is taking a big bite'. Find frequency of the letter 's'

SOLUTION: 4

PROBLEM: Sentence: 'there is a old green and white bus in this photo'. Find frequency of the letter 'i'

SOLUTION:
4