Data for Hermann Corporation are shown below:

Per Unit Percent of Sales

Selling price $ $65100\%$

Variable expenses $3960$

Contribution margin $ $2640\%$

fixed expenses are $$73,000$ per month and the company is selling $4,300$ units per month.

$2-$a$.$ Refer to the original data. How much will net operating income increase $($decrease$)$ per month if the company uses higher$-$quality components that increase the variable expense by $$5$ per unit and increase unit sales by $25\%.$

$2-$b$.$ Should the higher$-$quality components be used?