Oslo Company prepared the following contribution format income statement based on a sales volume of 1,000 units (the relevant range of production is 500 units to 1,500 units): Sales $ 20,000 Variable expenses 12,000 Contribution margin 8,000 Fixed expenses 6,000 Net operating income $ 2,000 6. Required information 13. Using the degree of operating leverage, what is the estimated percent increase in net operating income of a 5% increase in sales? 7. Required information 7. If the variable cost per unit increases by $1, spending on advertising increases by $1,500, and unit sales increase by 250 units, what would be the net operating income?