The document discusses the economic interpretations of primal and dual linear programming. It explains that the primal problem seeks to maximize revenue under limited resources by allocating activities across resources. The dual variables represent the worth per unit of each resource. The dual constraints represent the "imputed cost" per unit of each resource, and the reduced cost of an activity is the imputed cost of resources needed to produce it. The optimality condition of the simplex method states that an unused activity should only increase if its reduced cost is negative, meaning its revenue exceeds its imputed costs, making it economically advantageous. An example of assembling toys illustrates how reduced cost can determine whether a toy is economically attractive to produce.