Percent of Per Unit Sales Selling price Variable expenses $150 100% 60 40% Contribution margin $ 90 60% The company is currently selling 7,000 units per month. Fixed expenses are $214,000 per month. The marketing manager believes that a $7,500 increase in the monthly advertising budget would result in a 190 unit increase in monthly sales. What should be the overall effect on the company's monthly net operating income of this change? Multiple Choice Increase of $9,600 O decrease of $9,600 decrease of $7.500 Increase of $17,100