marigold corp. sells its product for $7100 per unit. unit variable cost are: manufacturing, $3600, and selling and administrative, $75. fixed costs are: $16000 manufacturing overhead and $20000 selling and administrative. there was no beginning inventory at 1/1/21. production was 20 units per year in 2021-2023. sales were 20 units in 2021, 16 units in 2022, and 24 units in 2023. net income under variable costing for 2023 is