Please show formula.

What is the price of a Bond with $1,000 face value, paying an 8% coupon rate paid which is paid semi-annually, and it has a required return of 7.5% if: A. The bond has 16 years maturity? B. The bond has 20 years maturity? C. What is the Duration of the bond if it has 16 years maturity, given the above information? D. What is the Duration of the bond if it has 20 years maturity, given the above information