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 4,500 $ 8,735 32,000 21,139 $61,955 During October, the activity level was 7600 units, and the total costs incurred were $69.000. Required: a. Calculate the variable costs, fixed costs and mixed costs incurred during October October Variable cost Fored cost Mixed cost Next > b. Use the high-low method to calculate the cost formula for mixed cost. Do not round intermediate calculations and round your answers to 2 decimal places.)