Question

The A-1 Car Rental Agency charges $23 per day plus $.10 per mile. The EZ Rental Agency charges $30 per day and $.05 per mile. If x is miles and y is total cost, write the ordered pair (x,y) that shows at what point the two companies charge the same amount.

Answer 1

(140, 37)

Explanation:

If we are looking for the point where the 2 companies charge the same amount, we need to set the 2 cost function equal to each other and solve for the number of miles that makes the cost the same. The number of miles will also be the same at this cost. That means we need cost functions for each. x is the number of miles that is driven, our independent variable. If A-1 charges .10 per mile, the expression is .1x. If the flat fee is 23, regardless of how many miles you drive, you can expect to pay

y = .1x + 23

If EZ charges .05 per mile, the expression is .05x. If the flat fee is 30, regardless of how many miles you drive, you can expect to pay

y = .05x + 30

If we want to see where the cost functions are equal, we set the right sides of those equations equal to one another and solve for the number of miles that makes the cost the same.

.1x + 23 = .05x + 30 and

.05x = 7 so

x = 140 miles.

In order to find the cost we will pick one of the equations and sub in 140 for x and solve for y.

y = .1(140) + 23

y = 14 + 23

y = 37

The coordinate pair is (140 miles, $37)

This means that at 140 miles driven, the cost is $37 no matter which rental agency you choose.