Assume that AT&T stock is currently selling for $50 per share. Assume that you will purchase 200 shares. You have $3,000 of your own to invest and you will borrow an additional $7,000 from your broker at an interest rate of 5% per year (assume no service charge for the loan). The Maintenance Margin is 20%. If AT&T stock price falls to $20 per share over the year (at the end of the year), what is your rate of return if you buy on margin? Assume that IBM pays no dividends over the year.