Refer to the original data (below). The president feels that it would be unwise to change the selling price. Instead, she wants to increase the sales...

Refer to the original data (below). The president feels that it would be unwise to change the selling price. Instead, she wants to increase the sales commission by $2 per unit. She thinks that this move, combined with some increase in advertising, would increase sales to 40,000 units compared to 20,000 last year. By how much could advertising be increased with profits remaining unchanged? Do not prepare an income statement; use the incremental analysis approach.