A company has the following work in process inventory information: 6,000 units were in beginning inventory. 12,000 units were started. 5,000 units were in ending inventory. Beginning inventory is 60% complete for materials and 40% complete for conversion. Ending inventory is 30% complete for materials and 80% complete for conversion. What is the number of equivalent units for materials using weighted average process costing?

Please show a breakdown of all math and equations used.