If you could show the formulas, that would be fantastic!

North Star Company is considering whether or not to refund a $115 million, 5.75% coupon, 25-year bond issue that was sold 9 years ago. It is amortizing $5.5 million of flotation costs on the 5.75% bonds over the issue's 25-year life. Star's investment bankers have indicated that the company could soil a new 16-year issue at an interest rate of 4% In today's market Neither they nor Star's management anticipate that interest rates will fall below 4% any time soon, but there is a chance that interest rates will increase. A call premium of 5% would be required to retire the old bonds, and flotation costs on the new issue would amount to $4.6 million. Star's marginal federal-plus-state tax rate is 40 percent. Perform a complete bond refunding analysis. What is the bond refunding's NPV? North Star Company is considering whether or not to refund a $115 million, 5.75% coupon, 25-year bond issue that was sold 9 years ago. It is amortizing $5.5 million of flotation costs on the 5.75% bonds over the issue's 25-year life. Star's investment bankers have indicated that the company could soil a new 16-year issue at an interest rate of 4% In today's market Neither they nor Star's management anticipate that interest rates will fall below 4% any time soon, but there is a chance that interest rates will increase. A call premium of 5% would be required to retire the old bonds, and flotation costs on the new issue would amount to $4.6 million. Star's marginal federal-plus-state tax rate is 40 percent. Perform a complete bond refunding analysis. What is the bond refunding's NPV