Please help me figure out the refund analysis and calculate the bond refunding NPV.

if I refund a-

• $250 million, 12% coupon, 30-year bond issue that was sold 5 years ago.
• amortizing $6 million of floatation costs on the 12% bonds over the issue's 30-year life.
• I could sell a new 25-year issue at an interest rate of 10% in today's market.
• Interest rates should not fall below 10%

A call premium of 11% would be required to retire the old bonds

• flotation costs on the new issue would equal $3 million
• marginal federal-plus-state tax rate is 40%
• The new bonds would be issued 1 month before the old bonds are called
• the proceeds would be invested in short-term government securities returning 7% annually during the interim period.