A truck for hauling coal has an estimated net initial cost of $60,000 and is expected to give service for 250,000 kilometres (KM), resulting in a $5,000 salvage value. The units-of-production method is used for book depreciation calculations. The expected usage of the truck over the next few years is estimated to be:

Year	1	2	3	4	5
Usage (Km)	30,000	35,000	40,000	45,000	50,000

The book value of the truck at the end of year 4 is