on march 31, 2024, a company purchased the right to remove gravel from an old rock quarry. the gravel is to be sold as roadbed for highway construction. the cost of the quarry rights was $231,000, with estimated salable rock of 30,000 tons. during 2024, the company loaded and sold 4,200 tons of rock and estimated that 25,800 tons remained on december 31, 2024. on january 1, 2025, the company estimated that 8,400 tons still remained. during 2025, the company loaded and sold 12,600 tons. the company uses the units-of-production method.