A department of Delta Company incurred the following costs for the month of June. 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 4,500 $ 8,100 30,000 20,800 Mixed costs Total costs $ 58,900 During July, the activity level was 9,000 units, and the total costs incurred were $69,000. Required: a. Calculate the variable costs, fixed costs, and mixed costs incurred during July. b. Use the high-low method to calculate the cost formula for mixed cost. Complete this question by entering your answers in the tabs below. Required A Required B Calculate the variable costs, fixed costs, and mixed costs incurred during July. July Variable cost Fixed cost Mixed cost < Required A Required B >