Question

The cost of a parking permit consists of a one-time administration fee plus a monthly fee. A permit purchased for 12 months costs $660. A permit purchased for 15 months costs $810.

What is the administration fee?

$50
$54
$55
$60

Answer 1

Let A be the administration fee and m the monthly fee.

A + 12m = 660
A + 15m = 810

Subtract: 3m = 150 → m = 50.
Then A = 660 − 12(50) = 660 − 600 = 60.

Answer: $60.