FACalculation Cost of sale

Hi I am working on multi-task question and I came across this information given for the preparation of the financial. The inventories at the close of business on 31 December 2009 were valued at cost of $ 19871.Include in this balance was an inventory line costing $4000 that, due to the change in legislation in now illegal. Clerc could rectify the items at a cost of $ 2,500 and plans to do so. The items usually retail to customer at $6000. Additional information given in the question. Opening inventory 17331 Purchase 130562 Working Opening inventory 17331 Purchase 130562 Less closing inventory (19871- (4000-3500) ( 19371) Cost of sale 128522 Could you please explain to me how to get (4000-3500) figure? No problem at all about 4000 but I could not figure out 3500. Thanks a lot Gabbi