ZB Toys started 2017 with no inventories. During the year, their expected and actual production was 30,000 units, of which they sold 24,000 units at $50 each. Cost data for the year is as follows: (Click the icon to view the cost data.) Calculate ZB Toys ' operating income under (a) variable costing, and (b) absorption costing. Explain why operating income differs under the two approaches