Helen believes the shares of Alphamart Inc. are overvalued. She sells short 4,500 shares at $19.00 per share. The margin requirement for Alphamart is 50% and Helen contributes the minimum necessary. One month later Helen has been proven right - the shares have dropped to $17.50. Helen covers her short. a. How much did Helen's account increase in value by, before interest and commissions? (2 marks) Number b. Assume Helen was wrong and Alphamart's shares increase to $20.90. Assuming Helen continues to contribute the required margin, how much margin will now be in her account? (3 marks) Number c. Assume Helen covers her short at $20.90. What percentage of her original contribution did Helen lose on this trade? Round your answer to two decimal places. (2 marks) Number