Every linear programming problem has two alternative forms, the primal and the dual. The
objective of the primal model is to maximize the outputs, where limiting by the inputs. It is as
shown in Formula 1. The primal formulation approached the problem from the standpoint of
maximizing the outputs whereas the dual model will be concerned with minimizing the inputs
(Hughes & Grawiog, 1973). In maximizing output model, we are looking for the output the
companies should achieved base on the inputs given. In minimizing input model, we are looking
for how much input should reduce by maintaining the current level of output.