TASK DEFINITION: In this task, you need to replace a letter in the sentence with another given letter.
PROBLEM: Sentence: 'the people are in the library working and studying'. Replace the letter 'r' with 'g' in the sentence.

SOLUTION: the people age in the libgagy wogking and studying

PROBLEM: Sentence: 'a young man playing tennis and preparing to hit the ball'. Replace the letter 'e' with 'c' in the sentence.

SOLUTION: a young man playing tcnnis and prcparing to hit thc ball

PROBLEM: Sentence: 'a man posing in a store in front of displays of shirts and ties, and a rack of suit jackets'. Replace the letter 's' with 'v' in the sentence.

SOLUTION:
a man poving in a vtore in front of divplayv of vhirtv and tiev, and a rack of vuit jacketv