i want the correct and make sense answers, also having clear calculation step. Thanks a lot.

3. You are bearish on MRTC and decide to sell short 2,500 shares at the current market price of $50 per share. a. How much in cash or securities must you put into your brokerage account if the broker's initial margin requirement is 60% of the value of the short position? b. If you earn no interest on the funds in your margin account, what will be your rate of return after one year if MRTC is selling at $45 per share? Assume that MRTC pays no dividends. c. How high can the price of the stock go before you get a margin call if the maintenance margin is 35% of the value of the short position? (10 marks)