Feather Friends, Inc., distributes a high-quality wooden birdhouse that sells for $80 per unit. Variable expenses are $40.00 per unit, and fixed expenses total $180,000 per year. Its operating results for last year were as follows:

Sales 2160000

Variable expenses 1080000

Contribution margin 1080000

Fixed expenses 180000

Net operating income 900000

The president does not want to change the selling price. Instead, he wants to increase the sales commission by $2.40 per unit. He thinks that this move, combined with some increase in advertising, would increase this year's sales by 25%. How much could the president increase this year's advertising expense and still earn the same $900,000 net operating income as last year?