Jack asked Jill to marry$$ him, and she has accepted under one$$ condition: Jack must buy her a new $$$$320,000$Rolls$-$Royce Phantom. Jack currently has $$$$20,350$ that he may invest. He has found a mutual fund with an expected annual return of $7\mathrm{.}5$ percent in which he will place the money. How long will it take Jack to win$$ Jill's hand in$$ marriage? Ignore taxes and inflation.