Having just received her tax return, Amanda wants to buy a car. She knows that her friend Mary wants to sell her old Corolla to buy a Ford Falcon. On Saturday, Amanda goes to Mary's house and offers her to buy her Corolla for a price of $ 5,500. Mary is not sure whether or not to accept Amanda's offer, and she promises Amanda to give an answer by the following morning. Before reaching a decision about her old Corolla, Mary visits the Ford dealer to ask about the Falcon model that she wants to buy.A Ford representative told Mary that her Corolla's price was $6,000 and the dealer was ready to accept her old car as down payment for a brand new Falcon. After her meeting with the Ford representative, Mary called Amanda and told her on the phone that she was willing to sell her Corolla for the amount of $6,300. Amanda replied that she would pay $6,200 and she would collect the car the following day. When Amanda arrived at Mary's house the following day to collect the car, she found that Amanda had sold it to the Ford dealer for the amount of $ 6,300. Amanda is upset and she comes to you to know whether she had previously formed a contract with Mary. Please advise Amanda by referring to the relevant principles of common law. In your advice you must clearly identify the offers, counter offers, acceptance and agreement, if there is any, from the communications between Mary and Amanda.