Jonathan knit some scarves to sell at a local arts-and-crafts show. The function r(x)=13x models the amount of money, in dollars, he brings in by selling x scarves. The function c(x)=6x models the cost, in dollars, for Jonathan to produce x scarves. It also costs Jonathan $58 to get a booth at the show. Which of the following functions p(x) models his profit for selling x scarves?