Data concerning Wislocki Corporation's single product appear below:

	Per Unit			Percent of Sales
Selling price	$	160			100	%
Variable expenses		40			25	%
Contribution margin	$	120			75	%

Fixed expenses are $1,041,000 per month. The company is currently selling 9,600 units per month.

Required:

The marketing manager would like to introduce sales commissions as an incentive for the sales staff. The marketing manager has proposed a commission of $13 per unit. In exchange, the sales staff would accept an overall decrease in their salaries of $105,000 per month. The marketing manager predicts that introducing this sales incentive would increase monthly sales by 400 units. What should be the overall effect on the company's monthly net operating income of this change?

Question: change in net operating income = ?