Shelhorse Corporation produces and sells a single product. Data concerning that product appear below: Percent of Sales 100% 20% Per Unit $ 200 40 $ 160 Selling price Variable expenses Contribution margin 80% Fixed expenses are $361,000 per month. The company is currently selling 5,600 units per month. Required: The marketing manager believes that a $18,000 increase in the monthly advertising budget would result in a 140 unit increase in monthly sales. What should be the overall effect on the company's monthly net operating income of this change? Change in net operating income