Problem scenario: Identify the relevant issues, state the applicable principles of law, supported by authority, and apply the law to the given facts to arrive at a conclusion.

Scenario (the facts) :

John owns a Honda Civic car which he wishes to sell.

He emails Joan, who he knows is looking for a car, on 1st December: Would you like to buy my car? It is yours for $8,000.

On December 2 Joan replies: Great - can I pay you $5,000 now and the balance of $3,000 in one month's time?

John responds: I really need the $8,000 now as I need to purchase a new car.

On the evening of December 2 John receives an email from Donald: I hear you are selling your Honda Civic, I will give you $9,500 for it. Unless I hear from you to the contrary I will bring the cash and pick the car up at midday tomorrow.

As John is reading Donald's email he sees in his email box that he has a missed voicemail from Joan - since he would rather sell the car to Donald whatever Joan says, he deletes it without listening to it.

The message Joan had left was as follows: Hi John, I understand, mum will advance me the other $3,000 so I will buy the car for $8,000 cash - when can I collect it? Required: On the basis of the law governing the essentials of a valid contract, explain whether John has avalid contract with Joan or Donald or neither or both of them.

Your argument, naturally, should be supported by appropriate legal authorities.