Data concerning Runnells Corporation's single and sells a product. Data co cerning that product appear below: Per Unit Percent of Sales Selling price $180 100% Variable expenses 90 50% Contribution margin $ 90 50% The company is currently selling 6,700 units per month. Fixed expenses are $547,700 per month. The marketing manager believes that a $7,100 increase in the monthly advertising budget would result in a 170 unit increase in monthly sales. What should be the overall effect on the company's monthly net operating income of this change? Decrease of $8,200 Decrease of $7,100 Increase of $8,200 Increase of $15,300