List PV, N, FV, PMT and I/Y

Five years ago a borrower incurred a mortgage for $80,000 at 10% for 30 years, monthly payments. Currently the market rate is 8% on 25-year mortgages. The existing mortgage has a prepayment penalty of 5% of the outstanding balance and the lender will charge 4% financing cost on a new loan. A. If the borrower plans to hold either mortgage for the next 25 years (we suppose the term of new loan is 25 years, which equals to the number of periods the old loan remains) 1) Without discounting, should he/she refinance, what is the net benefits? 2) With discounting, should he he refinance, what is the net benefits