Andrew just purchased a lounge furniture set for his new house from Things You Do Not Need Ltd (TYN). Now Andrew has to sell his old lounge furniture set in order to make room for the new one.

Andrew posts an advertisement online to sell the old couch. The advertisement reads "Lounge furniture set for sale, from $2,000. Delivery not included"

The next morning, Saturday 1 March, Tiffany responds to Andrew's advertisement by message offering to buy the couch for $1,800. Tiffany leaves her phone number for Andrew and asks that he calls her to discuss the offer.

Later on 1 March, Andrew telephones Tiffany and tells her that the price for the couch is $2,000 plus $100 delivery fee. Tiffany asks if she can have a little time to think about the offer and Andrew says, "Certainly. I will leave the offer open for 7 days until Saturday 7 March. Please pay $100 deposit by the end of the day to my bank account" Andrew gives Tiffany his bank details.

On Monday 3 March, Tiffany posts a letter to Andrew agreeing to buy the couch for $2,000 plus $100 delivery fee. She also attaches a cheque for the deposit ($100)

Two days later, on Wednesday 5 March, Andrew is having coffee with a close friend Natalie. Andrew explains that he is selling his old furniture set. Natalie is interested in the furniture and offers Andrew $2,000 in cash for the couch and says she will pick it up that day. Andrew accepts and immediately rings Tiffany and tells Tiffany that she has sold the couch to Natalie. Tiffany does not answer the phone, so Andrew sends her a text message explaining that he has sold the couch.

Advise Andrew as to his contractual obligations in respect of the couch