How can the formula for the present value of an ordinary annuity be modified to find the

Question:

How can the formula for the present value of an ordinary be modified to find the present value of an due?

Annuity
An annuity is a series of equal payment made at equal intervals during a period of time. In other words annuity is a contract between insurer and insurance company in which insurer make a lump-sum payment or a series of payment and, in return,...