Please explain in the best detail possible on how to get these results

THIS PROBLEM HAS MULTIPLE QUESTIONS. NINE months ago, you purchased 500 shares of stock on margin. The initial margin requirement on your account is 60% and the maintenance margin is 40%. The call money rate is 3.5\% and you pay 1.2% above that rate. The purchase price was $15 per share. Today, you sold these shares for $18 each. QUESTION\#1. Your new margin is QUESTION \#2. Your effective annual return (EAR) is QUESTION \#3. Suppose you sold the stock at $14 per share, instead of $18 per share. The new margin would be and you have received a margin call