White Corporation uses the FIFO method for internal reporting purposes and LIFO for external reporting purposes. The balance in the LIFO Reserve account at the end of 2010 was $80,000. The balance in the same account at the end of 2011 is $120,000. Whites Cost of Goods Sold account has a balance of $600,000 from sales transactions recorded during the year. What amount should White report as Cost of Goods Sold in the 2011 income statement?

ans: $640,000. Can you show me how?