Peter is going through a mid-life crisis and this prompts him to try to buy his "dream" car: a green Holden Torana owned by his former boss, Michael. Peter sends the following email to Michael: "Do you still have the epic Torana? If so, I am prepared to offer you $100,000 you will no doubt be aware that this is way over the car's market value. But my offer will remain open for only three weeks". Michael, on the basis of this offer, buys his two twin children a car each. Before the three weeks expired, but after Michael had bought cars for his children , Peter advises Michael that he is withdrawing his offer as his wife is threatening to leave him if he goes ahead with the purchase of the Torana. Michael is upset and tells Peter that since the three weeks have not yet passed, Peter's $100,000 offer still stands. Is Peter required to proceed with the purchase of Michael's Torona for $100,000, according to the law of contract? Please refer to any relevant legal cases and/or legislation to support your arguments.