Final answer:
The given constraint X13+X23-X34 >= 50 indicates that the flow from node 3 to node 4 is at least 50 (option c).
Step-by-step explanation:
The given constraint X13+X23-X34 >= 50 indicates that the flow from node 3 to node 4 is at least 50 (option c). Let's break down the equation:
- X13 represents the flow from node 1 to node 3.
- X23 represents the flow from node 2 to node 3.
- X34 represents the flow from node 3 to node 4.
Hence, the constraint ensures that the flow from node 3 to node 4 is greater than or equal to 50.