用lingo編程求DEA最優解

1800*x1 + 1000*x2 + 800*x3 + 900*x4 >= 1800;

200*x1 + 350*x2 + 450*x3 + 420*x4 >= 200;

1600*x1 + 1000*x2 + 1300*x3 + 1500*x4 >= 1600;

15*x1 + 20*x2 + 21*x3 +20*x4 <= 15*E;

140*x1 + 130*x2 + 120*x3 + 135*x4 <= 140*E;

x1 + x2 + x3 + x4 = 1;