Marco owed his father $210 and began paying him back $20 at the end of each week, beginning November 1. Joni owed her father $130 and began paying back $10 at the end of each week, beginning on the same day. What Marco owed his father in dollars at the end of n weeks can be represented by f(n) = 210 − 20n. What Joni owed her father in dollars at the end of n weeks can be represented by g(n) = 130 - 10n. Find the value of n for which f(n) = g(n). What does that value mean in this situation?