Data for Hermann Corporation are shown below:

Fixed expenses are $$77,000$ per month and the company is selling $2,600$ units per month.

Required:

$1-$a$.$ How much will net operating income increase $($decrease$)$ per month if the monthly advertising budget increases by $$8,200,$ the

monthly sales volume increases by $100$ units, and the total monthly sales increase by $$8,500?$

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