A garage charged Mr. Tilton $48 in parts and $36/h in labor. How many hours did the garage spend on Mr. Tilton’s car if the total bill was $156?

Question

mathmale · Answer

What would a formula for the total bill look like?  It'd contain an expression for the cost of parts and then another expression for the total cost of labor, and would resemble the equation of a straight line.  Try coughing up such a formula.

Then substitute into this formula what you know:  Total bill:  $156, Parts:  $48, and that expression for the total cost of labor.

Solve this equation for x (the number of hours spent by the mechanics).