Sales price per pair of sandals

$20

Variable expenses per pair of sandals14'

Contribution margin per pair of sandals$6

Fixed expenses per year:

Building rental$1,800

Equipment depreciation

1,800

Selling1,800

Administrative6,600

Total fixed expenses$12,000

During the first year, the store sold only 3,000 pairs of sandals and reported the following operating results:

Sales (3,000 pairs)$60,000

Variable expenses42,000

Contribution margin18,000

Fixed expenses12,000

Net operating income$6,0

Use the degree of operating leverage, what would be the expected percentage increase in net operating income if Angie is able to increase sales by 50%?