please give the answers and explain it thankss

3. You are bullish on ITC stock. The current market price is $80 per share, and you have $300,000 of your own to invest. You borrow an additional $500,000 from your broker at an interest rate of 2% per week and invest $800,000 in the stock. ITC pays no dividends. a. Suppose the price of ITC stock falls immediately after your purchase. The maintenance margin is 30%. How low can the price of ITC stock fall before you receive a margin call? b. After 2 weeks, calculate your rate of return if the price of ITC stock has gone up by 20%