Data for AOK Corporation are shown below: Per Unit Percent of Sales Selling price $ 80 100 % Variable expenses 44 55 Contribution margin $ 36 45 % Fixed expenses are $76,000 per month and the company is selling 2,500 units per month. Required: How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $6,100 and monthly sales increase by $14,400.