2. On 1 July, Au offers to sell his yacht, the Valkyrie, to Wong for $30,000 and promises to keep the offer open until 7 July. Is there a contract in the following situations? Use the IRAC method (Issue, Rule, Application and Conclusion) to answer the following questions

2a. On 2 July, Wong sends a message to Au: 'Will you accept $25,000?' Au replies: '$25,000 unacceptable.' Wong then sends a further message: 'Agree to your asking price.'

2b. On 4 July, Wong posts a letter to Au accepting the offer. Later the same day, he changes his mind and telephones Au who is not at home, so he leaves a message with Au's wife: 'Ignore my letter of today.'

2c. On 11 July, Wong posts a letter of acceptance.