A department adds all raw materials to a process at the beginning of the process and incurs conversion costs uniformly throughout the process. For the month of January, there were no units in the beginning work in process inventory: 90400 units were started into production in January; and there were 20400 units that were 45% complete in the ending work in process inventory at the end of January. What were the equivalent units of production for conversion costs for the month of January? 70000 equivalent units. 81220 equivalent units. 79180 equivalent units. 90400 equivalent units.