We claimed that the Repco model could either constrain the units produced to be greater than or equal to the units used by production or constrain the units sold to be nonnegative. Modify the model to...

We claimed that the Repco model could either constrain the units produced to be greater than or equal to the units used by production or constrain the units sold to be nonnegative. Modify the model to implement the latter (deleting the former), and verify that you get the same optimal solution.