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

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. B. If the borrower plans to hold either mortgage for 8 more years only (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