A product requires four steps to complete.
Step 1 takes 8 minutes
Step 2 takes 6 minutes
Step 3 takes 2 minutes
Step 4 takes 10 minutes
20% of all units produced requires rework. For reworking, they have to revisit steps 3 and 4. Each step is processed by one employee. Rework takes the same processing times as the first pass and always fixes the problem. What is the capacity of the process in units per minute?