Required information [The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Fixed expenses are $84,000 per month and the company is selling 2,600 units per month. Required: -a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $8,900, the nonthly sales volume increases by 100 units, and the total monthly sales increase by $12,000? -b. Should the advertising budget be increased? Complete this question by entering your answers in the tabs below. 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 ? (Do not round intermediate calculations.)