Dybala Corporation's produces and sells a single product. Data concerning that product appear below: Per Unit Percent of Sales Selling price $140 100% Variable expenses 70 50% Contribution margin $ 70 50% The company is currently selling 6,300 units per month. Fixed expenses are $385,300 per month. The marketing manager believes that a $6,700 increase in the monthly advertising budget would result in a 130 unit increase in monthly sales. What should be the overall effect on the company's monthly net operating income of this change? Decrease of $2,400 Increase of $9,100 Decrease of $6,700 Increase of $2,400