Lucia decided that it was time to sell her car. However, she was not certain of its value and so, when she advertised the car, she left out the price. When Matthew responded to the advertisement, he asked for the price. Lucia responded by saying, 'Oh, I don't know. I guess a fair price would be around a couple of thousand dollars'. When Matthew arrived the following day with $3000 for the car, Lucia told him that she really meant $3500.

Needed:

Does a contract exist? You must answer this question using the principles of Australian contract law.