need to solve the following problem

A pair of shoes that wholesales for $28.79 has the following costs:

Manufacturing Labor 2.25
Materials 4.95
Factory overhead, operating expense 8.5
Sales costs 4.5
Advertising 2.93
Research & Development 2
Interest 0.33
Net Income 3.33
                        
Which are variable, and which are fixed?

If output were to rise, what would happen to average total costs, and why?