Answer:
The rental costs for the two companies are equal at x = 40 miles.
Step-by-step explanation:
The total cost function for Company A is Ca = $90 + ($0.30/mile)x, where x is the number of miles driven during the one day of rental.
The total cost function for Company B is Cb = $70 + ($0.80)x.
Setting these two formulas = to one another and solving for x, we get:
$90 + ($0.30/mile)x = $70 + ($0.80)x
First, subtract $70 from both sides, obtaining:
$20 + ($0.30/mile)x = ($0.80)x
Subtracting ($0.30/mile)x from both sides results in:
$20 = ($0.50/mile)x
Dividing both sides by ($0.50/mile) results in
x = ($20) / ($0.50/mile) = 40 miles
The rental costs for the two companies are equal at x = 40 miles.
