You became very successful just recently and are looking for some promising investment. You have been offered the following investment opportunity in China: if you invest $18,000 today, you will receive $6,000 two years from now, $8,000 four years from now, and $8,000 six years from now. a) What is the NPV of the opportunity if the interest rate is 4% per year? Should you take this opportunity? b) What is the NPV of the opportunity if the interest rate is 2% per year? Should you take this opportunity?