What is the difference between simple and compound interest?

You are bearish on telecom and decide to sell short 100 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 50% of the value of the short position? b. how high can the price of the stock go before you get a margin call if the maintenance margin is 30% of the value of the short position? (input the amount as a positive value. round your answer to 2 decimal places.)