What is the present worth of the following series of payments:

a) $800 at the end of each year for 12 years, at 5.8% interest compounded annually.

b) $2500 at the end of each year for 10 years, at 8.5% interest compounded annually.

c) $900 at the end of each year for 5 years, at 7.25% interest compounded annually.

d) $5500 at the end of each year for 8 years at 8.75% interest compounded annually