E22-10 Three college friends open an off-campus shop named Campus Sweats. They plan to sell a standard sweatshirt for $18 and a fancier version for $22. The $18 sweatshirt costs them $10, and the $22 sweatshirt costs them $12. The friends expect to sell two fancy sweatshirts for every three standard sweatshirts. Their monthly fixed expenses are $9.680. How many of each type of sweatshirt must they sell monthly to break even? To earn $6.600?