If an investor purchases a stock that appreciates from $40 per share to $60 per share over that six-month period, what is his/her return with 50% margin? Assume a 5% annual interest rate on the margin. What is the return assuming no margin? What is his/her return if the stock depreciates from $40 to $20 (assuming the same annual interest rate on margin)? What is the return assuming no margin? ?