QUESTION: Fix punctuation: He also earned extra money by making mathematical instruments of exceptional quality which he sold
ANS: He also earned extra money by making mathematical instruments of exceptional quality which he sold.

QUESTION: Fix punctuation: Use arrow keys to drive and space bar to hand brake the cars and make them slide easily in the
ANS: Use arrow keys to drive, and space bar to hand brake the cars and make them slide easily in the

QUESTION: Fix punctuation: By the way I had the best holiday ever
ANS: By the way, I had the best holiday ever!

QUESTION: Fix punctuation: In addition the clean airconditioned rooms and showering facilities help to make every visit a pleasurable experience
ANS:
In addition, the clean air-conditioned rooms and showering facilities help to make every visit a pleasurable experience.