Mary values one game of golf a month at $40, a second game a month at $30, a third game at $20, a fourth game at $15, and a fifth game at

$5. She would never play more than five times a month, even if golf were free. If each game costs $25, how many will she play? If, instead she can join the golf club, pay monthly dues, and play for “free,” how much, at most, would she be willing to pay in monthly dues? Suppose she must join the club to play golf: How much in monthly dues would she be willing to pay?