Can you help me with these questions? (Show your work). Thank you.

1. Joseph bought 100 shares of stock at a price of $24 a share. He used his 70% margin account to make the purchase. Joseph sold his stock after a year for $20 a share. Ignoring margin interest and trading costs, what is Joseph's return on investor's equity for this investment?
2. Jessica purchased 200 shares of stock at $38 using her 70% margin account. Her maintenance margin is 40%.Jessica has no other securities in her account. At what price will she receive a margin call?
3. Emily bought 200 shares of ABC Co. stock for $29.00 per share on 60% margin. Assume she holds the stock for one year and that her interest costs will be $80 over the holding period. Ignoring commissions, what is her percentage return (loss) on invested capital if the stock price went down 10%?
4. Gerry bought 100 shares of stock for $30.00 per share on 70% margin. Assume Gerry holds the stock for one year and that his interest costs will be $45 over the holding period. Gerry also received dividends amounting to $0.30 per share. Ignoring commissions, what is his percentage return on invested capital if he sells the stock for $34 a share?
5. Justin just made a margin purchase of 100 shares of DEF Corp. for $22.50 per share. The initial margin is 70%. The maintenance margin is 30%. How low can the price of each share of DEF be before Justin will have to add equity to his account?