TASK DEFINITION: In this task, you need to count the number of times the given letter appears in the given sentence.
PROBLEM: Sentence: 'a silver train crossing the road on tracks'. Find frequency of the letter 'r'

SOLUTION: 5

PROBLEM: Sentence: 'a young girl skiing down a snowy mountain'. Find frequency of the letter 'l'

SOLUTION: 1

PROBLEM: Sentence: 'a large red and white double decker bus is parked and empty'. Find frequency of the letter 'p'

SOLUTION:
2