Sharri places an ad in the paper offering to sell her piano for $4,000. Aaron writes to Sharri in response to the advertisement and offers to buy her piano for 3000. Sharri receives Aarons offer on Jan 3 and calls him to ask if he will consider increasing his offer. Aaron says he will think about it. Mary write Sharri offering to but it for 3,200. Sharri receives the letter on Jan 5 and writes back the same day saying she will sell it for 3,500. Mary receives the letter the same day Jan. 7 and writes back the same day advising Sharri that she accept the offer to buy it for 3,500. unfortunately, the letter is lost in the mail, Sharri never receives it. Aaron writes to Sharri on Jan 5 stating he will pay her 4,000 for her piano by paying 3,000 now and 1000 in one month. Sharri receives the letter on Jan 8 and calls Aaron the same day to confirm the payment terms are acceptable. Sharri then receives a call from Mary on Jan 9 in which she learns of Mary's acceptance by letter dated Jan 7. Sharri tells Mary she now wants 4,000 for the piano.

is Sharri bound to sell her piano to either Mary or Aaron? why or why not?