Well, to solve this you would divide 659 by 100 since that is the cost of 100 T-shirts, but you only need one. That means that one T-shirt costs $6.59. Then you would divide 600 by 50, which is 13.18, for the same reason. Then you subtract 13.18 from 6.59. (13.18-6.59) which would be 6.59. So the answer is 6.59