6. A 20 year annuity pays $50 at the beginning of each month during the first year, $55 at the beginning of each month during the second year, $60 at the beginning of each month during the third year, and so on. The nominal annual interest rate is 6% compounded monthly. Calculate the present value of the annuity.

7. An annuity pays 20 in three months, 25 in 1.25 years 30 in 2.25 years, and so on until the final payment at time 10.25 years. The annual effective interest rate is 5%. Calculate the present value of the annuity.