Details of the manufacturing activity in Amy Corporation's Assembly Department for the month of December is given below: Number of Units Labor and Overhead Percent Complete Work in process inventory, December 1 10,000 70% Started in assembly during the month 80,000 Work in process inventory, December 31 15,000 40% All materials are added at the beginning of processing in the Assembly Department Remember, labor and overhead are known as conversion costs The equivalent units for labor and overhead for the month, using the first in, first-out (FIFO) method, is 90.000 70,000 O 74,000 80,000