G is employed by a Canadian-controlled private corporation. In year 1,G was granted a stock option to acquire 1,000 shares from the treasury of his employer's corporation for $8 a share. At the time of receiving the option, the shares were valued at $10 per share. In year 3, G exercised his option and purchased 1,000 shares for $8,000. At the purchase date in year 3, the shares were valued at $15 per share. In year 6,G sold 1,000 shares for $20 per share. What amount is included in G's employment income for tax purposes in year 6