Jane knows that Andrew is studying Bachelor of Business at Fake University. She sends a

message to him on Facebook offering to sell her textbook to him for $80. She does shift work

and does not want to receive phone calls. In her message, she states that if he is interested, he

is to post a message to her on Facebook only. Andrew telephones Jane and leaves a message on

Jane's mobile with an offer to buy the textbook for $70. Jane was very annoyed when her

mobile rang while she was at work, so she contacted Andrew to reject his offer. Andrew has no

luck finding another second-hand textbook, so the next day, he posted another message to Jane

on Facebook to buy the textbook for $80. Jane replies that she has sold the textbook to another

student. Andrew replies that he accepted her offer of sale yesterday and that she has no right to

sell the book to another student.

Is there an agreement between Andrew and Jane? Why/Why not?

Please use relevant case law(Australian) (if any) to support your answer.