Required: 1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $8,100, the monthly sales volume increases by 100 units, and the total monthly sales increase by $8,000 ? 1-b. Should the advertising budget be increased? Complete this question by entering your answers in the tabs below. Should the advertising budget be increased? Required: 1-a. How much will net operating income increase (decrease) per month if the monthly advertising budget increases by $8,100, the monthly sales volume increases by 100 units, and the total monthly sales increase by $8,000 ? 1-b. Should the advertising budget be increased? Complete this question by entering your answers in the tabs below. Should the advertising budget be increased