The cost of holding a childrens birthday party at a rollerskating rink is a function of n, thr number of people in the party. The cost function, C, can be represented with this set of rules: C(n) = {150, 0 < n < 12 260, 12 < n < 20 400, 20
How much does it cost to have a party with 9 people? What about 20 people?

Graph the function on the coordinate plane.