a. No. Since the good that I am selling is inelastic considering the elasticity given in and outside Texas, having a lower price than non-Texan gas stations would have less impact on the quantity demanded.
b. The profit-maximizing price to charge a Texan for a car wash would be $12.
c. The profit-maximizing price to charge a Californian for a car wash would be $18.
(See attached for the calculations.)