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3. Langin Corporation has provided the following contribution format income statement. All questions concern situations that are within the relevant range. Sales (9,000 units) Variable expenses Contribution margin Fixed expenses Net operating income $540,000 324,000 216,000 204,000 $ 12,000 Required: a. What is the margin of safety percentage? b. Using the degree of operating leverage, what is the estimated percent increase in net operating income of a 15% increase in sales? Managerial Accounting SI Worksheet Chapter 5 Student Name Data concerning Phung Corporation's single product appear below: Per Unit Percent of Sales Selling price... $230 100% Variable expenses ..... 92 40% Contribution margin...... $ 138 60% Fixed expenses are $991,000 per month. The company is currently selling 8,000 units per month. Required: The marketing manager believes that a $23,000 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? Show your work