Answer: $78.25
Step-by-step explanation:
The Southern Division is willing to pay $78.25 to an outside company for this part that it needs.
In the same vein, the maximum therefore that they would be willing to pay for the Western Division should be $78.25 as well because anything higher than that would constitute an Opportunity Cost loss.
They should go for the cheaper option and if buying from the Western Division exceeds the $78.25 then it is loss on their part. Western Division should charge the same or less.