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 is closest to: (Round your intermediate calculations to 1 decimal place.)