Answer:
the answer is 6
Step-by-step explanation:
In this case we would need to have a combination of each plant with each customer. So the variable would be in this way (3C X 2P)
Customer1 Customer2 Customer3
Plant1 P1C1 P1C2 P1C3
Plant2 P2C1 P2C2 P2C3
Once you have this you can calculate the best combination to minimize the cost of shipping