please help me and explain this

Suppose you are going to receive $7,800 per year for 5 years. The appropriate discount rate is 7%. What is the present value of the payments if they are in the form of an ordinary annuity? What is the present value of the payments if they are in the form of an annuity due?What is the value today of $4,400 per year at a discount rate of 9% if the first payment is received 8 years from today and the last payment is received 25 years from today