Chapter 1, Problem 7P

I need help with this general accounting question using the proper accounting approach.

Fentos Medical Clinic measures its activity in terms of patient visits. Last month, the budgeted level of activity was 1,520 patient visits and the actual level of activity was 1,630 patient visits. The cost formula for administrative expenses is $3.00 per patient visit plus $18,200 per month. The actual administrative expense was $23,400. Last month, the spending variance for administrative expenses was _.

There were no beginning or ending inventories. What is the variable costing unit product cost?