Can you please show me how you get this $14,500? This is just practice homework.

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?

a. 12.100
b. 13,500
c. 14,000
d. 14,500 The answer how do I get that number? Can you explain it to me?

Thank you!!