Shambo Corporation has provided the following contribution format income statement. Assume that the following information is within the relevant range. Sales (3,000 units) $ 60,000 Variable expenses 42,000 Contribution margin 18,000 Fixed expenses 13,200 Net operating income $ 4,800 Using the degree of operating leverage, the estimated percent increase in net operating income as the result of a 20% increase in sales volume is closest to: Note: Round your intermediate calculations to 2 decimal places