Required information Skip to question [The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Per Unit Percent of Sales Selling price $ 60 100% Variable expenses 39 65 Contribution margin $ 21 35% Fixed expenses are $72,000 per month and the company is selling 4,200 units per month. Required: 1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $9,600, the monthly sales volume increases by 100 units, and the total monthly sales increase by $6,000? 1-b. Should the advertising budget be increased