Please provide how to solve using a financial calculator including PV of savings.

Five years ago, the State of Oklahoma issued $2,000,000 of 7% coupon, 20-year semiannual payment, tax-exempt bonds. The bonds had 5 years of call protection, but now the state can call the bonds if it chooses to do so. The call premium would be 6% of the face amount. Today 15-year, 5%, semiannual payment bonds can be sold at par, but flotation costs on this issue would be 2%. What is the net present value of the refunding? Because these are tax-exempt bonds, taxes are not relevant.