Discuss the applicable legal principles and advise whether there is an enforceable contract

Andrew and Erica are friends who are both enrolled in ACTG 2P40. On January 10, Andrew and Erica were discussing the sudden rise in value of shares of GME, a corporation listed on the Toronto Stock Exchange. The shares had risen from $10.00 per share on January 7 to $40.00 per share and were being widely promoted on READ-IT, a stock analysis website. Erica did not have a trading account and asked Andrew if he had any excess shares in his account that he would sell to her. Andrew offered to sell her 100 shares for $40.00 per share. Erica said she would let him know as soon as possible. On January 12, Erica told Andrew that she would accept his offer and delivered a cheque to him for $4,000.00. Andrew refused to accept the cheque since the shares were now trading for $42.00 per share. Erica commences an action against Andrew claiming that they have a valid contract. One week later the shares dropped to $16.00 per share. Andrew now agrees that there is a binding contract and sues Erica when she refuses to pay. Erica now claims that there is no contract and that in any event a contract cannot be enforced against her since she is only 17 and it was a "friendly" deal. Required: Discuss the applicable legal principles and advise whether there is an enforceable contract and, if so, on what terms. Does it make a difference whether the value of the shares increases or decreases