What does Willy say when Linda reminds him about the mortgage?

From the text:

Linda [buttoning up his jacket as he unbuttons it]: All told, about two hundred dollars would carry us, dear. But that includes the last payment on the mortgage. After this payment, Willy, the house belongs to us.

Willy: It’s twenty-five years!

Linda: Biff was nine years old when we bought it.

Willy: Well, that’s a great thing. To weather a twenty-five-year mortgage is—

Linda: It’s an accomplishment.