Store a has a promotion. if you buy three shirts, you get 25% off the total price of the three shirts. store b has the same shirts on sale with the promotion that if you buy three shirts, you get the third shirt at a 50% discount. store c has the same shirts on sale with a 10% discount. assuming the three stores have the shirts priced equally before any promotion or sale and assuming you want to buy three shirts, which store�s promotion or sale gives you the better deal?