15. The Unique Bookshelf Company is considering the purchase of a custom delivery van costing approximately $50,000. Using a discount rate of 20%, the present value of future cost savings is estimated at $51,200. To yield the 20% return, the actual cost of the van should not exceed the $50,000 estimate by more than: a. $50,000 b. $51,200 c. $25,000 d. $ 1,200 e. 20%