Hotel Snow White advertised a job vacancy for a receptionist. Mary applied for the job and she was employed agreeing to the terms and conditions specified in the written contract. After six months, she was asked to help out in the kitchen as a cook's assistant and she was paid less than the receptionist's pay, on the excuse that her present work has less responsibilities. Mary was not happy and wanted to quit her job immediately

1. Is the advertisement by the Hotel Snow White an offer in the law of contract?

2. Advise Mary on the issue of her quitting the job in line with the existing labour law.