Can you help me to do this by explain in details the calculation using the table ( table including components like t, CFs, PV, PV* delta T) and can you also help me to do another solution by using duration formula? And I also wonder can we do this by using excel? :( I don't know about duration model much ..

Example 5: U.S. Treasury bonds pay coupon interest semiannually. A Treasury bond has the face value of $1,000 and matures in two years. Calculate D when: (a) The annual coupon rate is 8 percent, and the annual yield to maturity (R) is 12 percent. (b) The annual coupon rate is 6 percent, and the annual yield to maturity (R) is 12 percent. (c) The annual coupon rate is 8 percent, and the annual yield to maturity (R) is 16 percent