A regular cash flow has a term of 15 years, paying out evenly at the end of each year is $650. If the first billing period occurs 6 years from today. The discount rate is 11%. a. Let's calculate the present value of this cash flow? b. Suppose the annual interest rate is 11% from year 1 to year 5, and 13% for the period after that. Let's recalculate the present value of this cash flow