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? Complete this question by entering your answers in the tabs below. Req 1A Req 1B 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.) Net operating income by