You sell 500 shares of Delta Airlines Inc. (DAL) short at a price of $50 per share. a. How much is your initial margin given margin requirements of 40%? b. If the stock declines to $40 per share what is your percentage gain or loss on the initial equity? How about a price increase to $55? c. After a price decline to $30, you would like to take out some cash. How much cash can you take out while maintaining the required 40% margin? d. Assuming a 30% maintenance margin, at what price will you get a margin call, and how much cash would you need to put up?