The cost of a parking permit consists of a one time administration fee plus a monthly fee. A per I purchased for 12 months costs $660. A permit purchased for 15 months costs $810. What is the administration fee?

Costs $60.

The difference between 12 months and 15 months is 3 months.

3 months for $150 without administration fee.

Because administration fee was paid at first of 12 months permit.

$50 for one month.

Now multiply 12 months by $50 you will get $600.

The remaining $60 is the administration fee.