Q7) (Fill in the black and show working out):

Suppose there are two operating systems: Mac and Windows, and n people are contemplating which system to purchase (each buys one or the other). The payoff of using a Mac is assumed to be 60 + 6m; where m is the number of Mac users. The payoff of choosing Windows is 3u; where u is the number of Windows users.

Then everyone buys Windows is a Nash equilibrium when n is greater than or equal to __________ .