2 case study, from Ragsdale. I'm not understanding how to solve the network modeling problem, especially the part from the demand and offer.

Hi, I need help with Old Dominion Energy 5.2 case study, from Ragsdale.

I'm not understanding how to solve the network modeling problem, especially the part from the demand and offer.

I don't understand how can I choose which is the demand and which is the offer.