On march 31,2009 M.Belotti purchased the right to remove gravel fron an old rock quarry. The gravel is to be sold as roadbed for highway construction. The cost of quarry rights was $164,000, with estimated salable rock of 20,000 tons. During 2009, Belotti loaded and sold 4000 tons of rock and estimatted 16000 tons remained at December 31,2009. During 2010, Belotti loaded and sold 8000 tons,but estimated at December 31,2010 that 12000 tons remained. What is depletion for 2010?