Many professional sports teams operate under a salary cap. This means that teams typically have a fixed amount of money that they can spend on players' salaries - that is, a salary cap. This is true of the National Basketball Association (NBA), for example. Suppose that the NBA has a salary cap of $100 million dollars, and a team has $30 million available to sign new players. That is, $70 million has already been committed to player salaries. The team has two further possibilities: either sign a star player for $30 million, or sign two good, solid supporting players for $15 million each. What is the opportunity cost of signing the star player, assuming the team spends its full budget?