Required a. Compute the balance in trade accounts payable as of December 31, Year 4. b. Compute the balance in retained earnings as of December 31, Year 4. c. Compute the balance in the inventory account as of December 31, Year 4. (Assume that the level of inventory did not change from last year.) (For all requirements, negative amounts should be indicated by a minus sign. Do not round intermediate calculations. Round your answers to the nearest whole dollar amount.)