A homeowner has a home financed with a $450,000 20-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?

Group of answer choices 4.1 years 6.0 years 2.9 years 8.4 years