You purchase 170 shares for $60 a share ($10,200), and after a year the price rises to $70. Calculate the percentage return on your investment if you bought the stock on margin and the margin requirement was (ignore commissions, dividends, and interest expense): a. 20 percent. Round your answer to one decimal place. % b. 55 percent. Round your answer to one decimal place. % C. 75 percent. Round your answer to one decimal place. %