[The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Per Unit Percent of Sales Selling price $ 90 100% Variable expenses 63 70 Contribution margin $ 27 30% Fixed expenses are $30,000 per month and the company is selling 2,000 units per month. Required: 1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $5,000, the monthly sales volume increases by 100 units, and the total monthly sales increase by $9,000? 1-b. Should the advertising budget be increased