Data for Hermann Corporation are shown below:

Per Unit Percent of Sales

Selling price $ $130100\%$

Variable expenses $7860$

Contribution margin $ $5240\%$

Fixed expenses are $$86,000$ per month and the company is selling $2,800$ units per month.

Exercise $5-5($Algo$)$ Part $1$

Required:

$1-$a$.$ How much will net operating income increase $($decrease$)$ per month if the monthly advertising budget increases by $$9,100,$ the monthly sales volume increases by $100$ units, and the total monthly sales increase by $$13,000?$