Gantner Company had the following department information about physical units and percentage of completion: Physical Units Work in process, May 1 (60%) 36,000 Completed and transferred out 90,000 Work in process, May 31 (40%) 30,000 If materials are added at the beginning of the production process, what is the total number of equivalent units for materials during May? Can you please clear out what kind of equation you used when solving this problem.