You purchase 70 shares for $70 a share ($4,900), and after a year the price falls to $60. 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. 25 percent. Use a minus sign to enter the amount as a negative value. Round your answer to one decimal place -57.1 b. 55 percent. Use a minus sign to enter the amount as a negative value. Round your answer to one decimal place. -122.7 " c. 85 percent. Use a minus sign to enter the amount as a negative value. Round your answer to one decimal place.