Kevin is an auto mechanic. He spends $3$ hours when he replaces the shocks on a car and $2$ hours when

he replaces the brakes. He works no more than $36$ hours a week. He routinely completes at least $4$

shocks replacements and $6$ brake replacements a week. If he charges $$400$ for labor replacing shocks

and $$250$ in labor for replacing brakes, how many jobs of each type should he complete a week to

maximize his income?