TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a passenger train that is going over a bridge'. Find frequency of the letter 't'

SOLUTION: 3

PROBLEM: Sentence: 'a teenager witting on a futon couch holding gaming controls in both hands'. Find frequency of the letter 'c'

SOLUTION: 3

PROBLEM: Sentence: 'a soldier standing in the middle of a flock of sheep'. Find frequency of the letter 'a'

SOLUTION:
3