Assume you sell short 600 shares of common stock at $50 per share, with initial margin at 50x. What would be your percentage markin and your rate of return on the short sale if you repurchase the stock at $45 per share? a) 409;25% b) 66,67%;25% c) 71,43%;20% d) 66,67%;20% e) 71.43%;25%