Mrs. Heileman occasionally drinks beer. (Guess which brand.) She consumes one case in 20 weeks. She can buy beer in disposable cans for S25.20 per case or for S24.00 per case of returnable bottles if she pays a S3.00 refundable deposit at the time of purchase. If her discount rate is 1/2 percent per week, how much in present value dollars does she save by buying the retumables and thereby losing the use of the S3.00 deposit for 20 weeks?