Describe the LIFO double-extension method. Using the following information, compute the index at December 31, 2012, applying the double-extension method to a LIFO pool consisting of 25,500 units of product A and 10,350 units of product B. The base-year cost of product A is $10.20 and of product B is $37.00. The price at December 31, 2012, for product A is $21.00 and for product B is $45.60. (Round to two decimal places.)