Sam is going to buy 300 shares of IBM at $45 on margin. He borrows 50% of the total cost of investment (initial margin). 17. Calculate rate of return if price increases to $48 after one year. 18. Calculate rate of return after Sam paid off the loan if price decreases to $40 after one year. 19. Calculate rate of return after Sam paid off the loan, interest on loan (6%), and $92 commission, if the price decreases to $40 after one year. 20. Calculate margin call price if maintenance margin is 25%