A homeowner has a home financed with a $350,000 15-year mortgage, paid monthly at 4.0% APR. After five years he receives $80,000 as an inheritance. If he pays this $80,000 toward his mortgage along with his regular payment by approximately how many years will it reduce the amount of time it takes him to pay off his mortgage? 5.5 years 3.6 years 2.3 years 6.4 years