If a company has offered me the following investment oppurtunity: $6000 at the end of each year for the first 5 years, $3000 at the end of each year for years 6 through 10, and $2000 at the end of each year from years 11 to through 20. How much should I be willing to pay for this investment if I required a 12 percent rate of return? And if I were to be able to receive the payments at the beginning of the year, what should I be willing to pay for this investment?