TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a couple of kids with rackets on a court'. Replace the letter 'u' with 'd' in the sentence.

SOLUTION: a codple of kids with rackets on a codrt

PROBLEM: Sentence: 'subway train approaching the platform of a subway station'. Replace the letter 'y' with 'c' in the sentence.

SOLUTION: subwac train approaching the platform of a subwac station

PROBLEM: Sentence: 'parking meter with cars and dirty street with walls'. Replace the letter 'n' with 'a' in the sentence.

SOLUTION:
parkiag meter with cars aad dirty street with walls