Question

Parking Garage A charges a flat rate per hour to park. The equation
y
=
9
x
represents the total cost,
y
, in dollars, of parking at Parking Garage A for
x
hours.



Parking Garage B charges a flat entry fee plus an hourly rate. The equation
y
=
6
x
+
15
represents the total cost,
y
, in dollars, of parking at Parking Garage B for
x
hours.



For which number of hours will parking at Parking Garage A be a better deal?

A.
4
hours

B.
5
hours

C.
6
hours

D.
9
hours

Answer 1

Solve 9x < 6x + 15:
3x < 15 → x < 5.

So Garage A is cheaper for fewer than 5 hours. From the choices, 4 hours. (Check: A = 9·4 = 36, B = 6·4 + 15 = 39.) Answer: A.