Data for Hermann Corporation are shown below:

Per Unit Percent of Sales

Selling price $ $110100\%$

Variable expenses $7770$

Contribution margin $ $3330\%$

Fixed expenses are $$82,000$ per month and the company is selling $3,500$ units per month.

Required:

$1-$a$.$ How much will net operating income increase $($decrease$)$ per month if the monthly advertising budget increases by $$8,700,$ the monthly sales volume increases by $100$ units, and the total monthly sales increase by $$11,000?$

$1-$b$.$ Should the advertising budget be increased?