Shelhorse Corporation produces and sells a single product. Data concerning that product appear below: Selling price Variable expenses Contribution margin Per Unit $ 240 120 $ 120 Percent of Sales 100% 50% 50% Fixed expenses are $352,000 per month. The company is currently selling 4,700 units per month. Required: The marketing manager believes that a $21,000 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? Change in net operating income