The director does not want to change the selling price which is $80 per unit. The variable expenses are $40 per unit. Instead, he wants to increase the sales commission by $2.40 per unit. He thinks that this move with some increase in advertising would increase this year's sales by 25%. How much could the director increase this year's advertising expense and still earn the same net operating income as the previous year?

Last year's data:

Sales $1,920,000 (24000 units * $80)

Variable expenses 960,000

Contribution margin 960,000

Fixed expenses 180,000

Net operating income $780,000