Please explain how to get each of these answers. Show work.

17. You invest $20,000 in Delta, $50,000 in KEY, and $30,000 in Dell. If the expected returns for Delta, KEY and Dell are 9%, 10% and 15%, respectively, then what is the portfolio's expected return? Answer: 11.30%

18. You receive a loan $6,000 today. You are required to pay back $30,000 in seven years. What is the annual interest rate of your loan? Answer: 25.85%

19. Jay is considering the purchase of a rental home. He plans to hold the house forever (leave it to his heirs). He forecasts that he will receive rent of $5,000 every month forever. How much should Jay pay for the rental property if his cost of capital in APR is 18% annually? Answer: $333,333.33

20. Trans American forecasted dividend for next year is $5.66 per share. The company's ROE is 11% and its plowback ratio is 40%. If Trans American's required return is 15% then what is the company's current stock price? Answer: $53.40