sw:ampl
ampl: option solver cplex;
ampl: model InventoryModel_Pr1_Pg104.mod;data InventoryModel_Pr1_Pg104.dat;
ampl: expand net_cost, inventory_balance;
minimize net_cost:
        5*x[1] + 8*x[2] + 4*x[3] + 7*x[4] + 2*s[0] + 2*s[1] + 2*s[2] + 2*s[3]
	- 6*s[4];
                                                                                         
subject to inventory_balance[1]:
        -x[1] - s[0] + s[1] = -50;
                                                                                         
subject to inventory_balance[2]:
        -x[2] - s[1] + s[2] = -65;
                                                                                         
subject to inventory_balance[3]:
        -x[3] - s[2] + s[3] = -100;
                                                                                         
subject to inventory_balance[4]:
        -x[4] - s[3] + s[4] = -70;
                                                                                         
ampl: solve;
CPLEX 8.0.0: optimal solution; objective 1180
0 dual simplex iterations (0 in phase I)
ampl: display net_cost, x,s; 
net_cost = 1180
                                                                                         
:    x     s     :=
0    .    115
1     0    65
2     0     0
3   170    70
4     0     0
;