Variable manufacturing costs are $100 per unit, and fixed manufacturing costs are $42,000. Sales are estimated to be 4,800 units. If an amount is zero, enter "O". Round intermediate calculations to the nearest cent and your final answers to the nearest dollar. a. How much would absorption costing operating income differ between a plan to produce 4,800 units and a plan to produce 6,000 units? S b. How much would variable costing operating income differ between the two production plans