with explain please

7. During 2005, Young Oil completed the last well from their drilling and production plat- form off the coast of Texas. Unrecovered costs on December 31, 2005, were $25 million, including $5 million in acquisition costs and $20 million in drilling and development costs. Total proved developed reserves were estimated to be 600,000 barrels as of January 1, 2005. Production during 2005 was 30,000 barrels. At the end of the life of the reser- voir, dismantlement costs are estimated to be $14 million and salvage value is estimated to be $1 million. Compure DD&A for 2005