Kevin is an auto mechanic. He spends 3 hours when he replaces the shocks on a car and 2 hours when replaced the brakes. He works no more than 54 hours a week. He routinely completes 4 shocks replacements and 6 replacements a week. If he charges $500 for labor replacing shocks and $250 in labor for replacing breaks, how many jobs of each type should he complete a week to maximize his income?

kevin should do __ shock replacements and ___ break replacements every week to maximize his weekly income