[The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Selling price Variable expenses Contribution margin Percent of Per Unit $120 Sales 100% 78 $42 65 35% Fixed expenses are $84,000 per month and the company is selling 2,600 units per month. Required: 1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $8,900, the monthly sales volume increases by 100 units, and the total monthly sales Increase by $12,000? 1-b. Should the advertising budget be increased