TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'a mobile phone and a set of keys on a key chain'. Replace the letter 's' with 'j' in the sentence.

SOLUTION: a mobile phone and a jet of keyj on a key chain

PROBLEM: Sentence: 'this poster is advertising high performance with a girl riding a bicycle and some taxis on the street'. Replace the letter 't' with 'f' in the sentence.

SOLUTION: fhis posfer is adverfising high performance wifh a girl riding a bicycle and some faxis on fhe sfreef

PROBLEM: Sentence: 'the red white and blue lights hang over the balcony'. Replace the letter 'n' with 'h' in the sentence.

SOLUTION:
the red white ahd blue lights hahg over the balcohy