Exercise $5-1$ The Effect of Changes in Activity on Net Operating Income $[$LO$5-1]$

Whirly Corporation's contribution format income statement for the most recent month is shown below:

Required:

$($Consider each case independently$)$:

What would be the revised net operating income per month if the sales volume increases by $80$ units?

What would be the revised net operating income per month if the sales volume decreases by $80$ units?

What would be the revised net operating income per month if the sales volume is $7,900$ units?