Please only work on this is you understand it. Please also provide how to solve only using excel, Thank you.

7-8 YIELD TO CALL Seven years ago the Templeton Company issued 20-year bonds with an 11% annual coupon rate at their $1,000 par value. The bonds had a 7.5% call premium, with 5 years of call protection. Today Templeton called the bonds. Compute the realized rate of return for an investor who purchased the bonds when they were issued and held them until they were called. Explain why the investor should or should not be happy that Templeton called them