[z] Min = 400*(x_1 + x_2 + x_3 + x_4) + 450*(y_1 + y_2 + y_3 + y_4) + 500*(z_1 + z_2 + z_3 + z_4) + 20*(i_1 + i_2 + i_3 + i_4);

d_1 = 40;
d_2 = 60;
d_3 = 75;
d_4 = 25;

x_1 <= 40;
x_2 <= 40;
x_3 <= 40;
x_4 <= 40;

y_1 <= 10;
y_2 <= 10;
y_3 <= 10;
y_4 <= 10;

x_1 + y_1 + z_1 <= 60;
x_2 + y_2 + z_2 <= 60;
x_3 + y_3 + z_3 <= 60;
x_4 + y_4 + z_4 <= 60;

i_1 = 10 + x_1 + y_1 + z_1 - d_1;
i_2 = i_1 + x_2 + y_2 + z_2 - d_2;
i_3 = i_2 + x_3 + y_3 + z_3 - d_3;
i_4 = i_3 + x_4 + y_4 + z_4 - d_4;

END