TB Problem Qu. 5-239 (Algo) Shelhorse Corporation produces and... Shelhorse Corporation produces and sells a single product. Data concerning that product appear below: Fixed expenses are $364,000 per month. The company is currently selling 5,900 units per month. Required: The marketing manager believes that a $21,000 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