(a) One day, Mary went to a boutique and tried on a dress displayed on the shelf of the shop. Then, she felt that the dress was not very comfortable and put it back on the shelf. However, the salesperson insisted Mary needed to pay for the dress because she already had a contract with the shop. Peter is the shopkeeper of a pet shop. Last week, Peter lost one of his Persian cats when taking it for bathing at his shop. He immediately put up a notice on the wall of his pet shop stating a reward of $1,000 for return of his cat. Recently, when Mary walked along the street, she found Peter's lost cat accidentally. Luckily, the cat wore a necklace with details of Peter's name and shop address. After Mary returned the cat to Peter, she discovered the notice on the wall and demanded the reward of $1,000.

(i) Advise Mary whether she is legally bound to buy the dress in the boutique. You are required to cite a relevant case in your explanation. (12 marks)

(ii) Advise Peter whether he is legally bound to pay the reward to Mary. You are required to cite a relevant case in your explanation. (10 marks)

(b) Ada contracted with Brian to repair her car for $5,000 and to complete the work within one week. Later, Brian told her that the repair work was very sophisticated and Ada promised to pay him an extra amount of $500.

Required: Advise Brian whether Ada is legally bound to pay him the extra amount of $500. You are required to cite relevant case(s) in your explanation. (8 marks)