Please help!!

JD Trader opens a brokerage account and purchases 400 shares of FINCEDU at $26 per share. He borrows $3,200 from his broker to help pay for the purchase. The interest rate on the loan is 10%.

a. What is the margin in JDs account when he first purchases the stock? b. If the share price falls to $15 per share by the end of the year, what is the remaining margin in his account? If the maintenance margin requirement is 45%, will he receive a margin call? (Show your calculation) c. If JD decides to sell 100 shares to pay down the debt, what is the new margin? d. What is the rate of return on his investment?