For last year, Lewisburn Manufacturing reported the following: Revenue $400,000 Beginning inventory of direct materials, January 1 Purchases of direct materials 22,000 140,000 Ending inventory of direct materials, December 31 Direct manufacturing labor Indirect manufacturing costs 33,000 118,000 40,000 30,000 Beginning inventory of finished goods, January 1 No beginning and no ending work in process Ending inventory of finished goods, December 31 Operating costs 36,000 140,000 What was Lewisburn's operating income? Show your calculations