What is the Formula to calculate cost per equivalent unit?

Double Eagle Corporation produces the prestigious "Double Eagle" Golf ball in one department using a process costing system. At the beginning of January, 10,000 golf balls were in work-in-process. During January, 20,000 more golf balls were started. The ending work-in-process included 6,000 balls which were 100 percent completed for direct materials, 75 percent completed for direct labor, and 75 percent completed for overhead.