Donnelly Corporation manufactures and sells T-shirts imprinted with college names and slogans. Last year, the shirts sold for $7.50 each, and the variable cost to manufacture them was $2.25 per unit. The company needed to sell 20,000 shirts to break even. The after-tax net income last year was $5,040. Donnelly's expectations for the coming year include the following:

The sales price of the T-shirts will be $9. .

Variable costs to manufacture each unit will increase by 33%. .

Fixed costs will increase by 10%. .

The income tax rate of 40% will be unchanged..

The number of T-shirts Donnelly Corporation must sell to break even in the coming year is: