[The following information applies to the questions displayed below.] Data for Hermann Corporation are shown below: Fixed expenses are $72,000 per month and the company is selling 4,200 units per month. equired: a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $9,600, the onthly sales volume increases by 100 units, and the total monthly sales incregse by $6,000 ? b. Should the advertising budget be increased