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This is the contribution margin, not the variable costs. Revenue minus variable costs equals the contribution margin. Therefore, revenue minus the contribution margin would equal variable costs.
This is total revenue multiplied by the tax rate. That is not variable costs.
This is the variable costs multiplied by (1 ? the tax rate). That is not variable expeses.
Revenue for sales of 1,000 units would be $30 × 1,000, or $30,000. The contribution margin is total revenue minus total variable costs. If the contribution margin ratio is 45% of revenue, the variable costs must be 100% ? 45%, or 55% of revenue. That is $30,000 × .55, or $16,500.