Exercises 18-45 (Algo) Full vs. Variable Costing [LO 18-3, 18-4] Security Technology Incorporated (STI) is a manufacturer of an electronic control system used in the manufacture of certain special- duty auto transmissions used primarily for police and military applications. The part sells for $44 per unit and STI had sales of 24,750 units in the current year, 2021. STI had no inventory on hand at the beginning of 2021 and is projecting sales of 28,250 units in 2022. STI is planning the same production level for 2022 as in 2021, 26,500 units. The variable manufacturing costs for STI are $15, and the variable selling costs are only $0.60 per unit. The fixed manufacturing costs are $238,500 per year, and the fixed selling costs are $650 per year. Required: 1. Prepare an income statement for each year using full costing. 2. Prepare an income statement for each year using variable costing. 3. Prepare a reconciliation of the difference each year in the operating income resulting from the full and variable costing methods.