Answer:
I could not find the exact missing details for your question so I will use a similar one that you can reference. See attached.
Fixed expenses will remain the same and only advertising and sales increased so;
Increase (decrease) in Net Operating income = Increase in sales * Contribution margin ratio - increase in expenses (advertising)
= 16,000 * 40% - 8,200
= 6,400 - 8,200
= -$1,800
Decrease of $1,800