Assume an initial margin requirement of 55% and maintance margin of 40%. An investor has $5,500 in cash and wishes to purchase ABC stock. ABC is currently trading at $100 per share and your broker charges 7.5% interest on margin loans. a) what is the return on equity of the margin position after one year when price rises to $120? b) what is the return on equity of the margin position after one year falls to $80? c) at what price would you receive a margin call?