General admission to the State Fair of Texas is $16.00. For guests to ride the various rides, they must use coupons that cost $0.50 each. The number of coupons needed for each ride varies. The representative function for the situation is C(x) = 0.5x + 16, where C(x) represents total cost as a function of the number of coupons, x. What is the domain for visiting and riding rides at the State Fair of Texas?