A department of Alpha Co. incurred the following costs for the month of September. Variable costs, and the variable portion of mixed costs, are a function of the number of units of activity: Activity level in units Variable costs Fixed costs Mixed costs Total costs 3,500 $ 6,300 30,000 20,500 $56,800 During October, the activity level was 9,000 units, and the total costs incurred were $68,500. Required: a. Calculate the variable costs, fixed costs, and mixed costs incurred during October. October Variable cost $ 16,200 Fixed cost $ 30,000 Mixed cost $ 22,300