Answer:
Step-by-step explanation:
The Total Cost formula for the Dealership is
$24 + ($99/hr)h, where h represents the number of hours of labor performed.
That for the Local Mechanic is
$45 + ($89/hr)h
We equate these two formulas so as to determine h, the number of hours elapsed so that the total costs are the same:
24 + 99h = 45 + 89h
Combining like terms, we get:
21 = 188h
Solve for h by dividing both sides by 188:
h = 188/21 = 8.95
The two bills would be equal 8.95 hours after commencement of the work.
Part b:
Dealership: $24 + ($99/hr)h. Evaluate this at 8.95 hrs: $910.05.
The dealership's bill would be more expensive AFTER 8.95 hours, because the rate of change ($99/hr) is greater in that case.
The local mechanic's total bill would be less up until the time that the car has been worked on for 8.95 hours.
$24 + ($99/hr)(8.95 hr) =
