please give me formula and answer to check my work. thank you

17. What is the current price of the stock in the preceding problem if the holding period is 20 years? (5) 18. What must be the dividend of a preferred stock with a current price of $80 and a yield of 12%? (5) 19. Express in percentage form the periodic rate in Problem #4. (5) 20. What is the future value after 20 years of a single deposit of $2000 earning 7.5% compounded monthly