! High Yield Case, Birge and Louveaux, Chapter 1

min 150x1 + 230x2+260x3  ! planting costs
+     238y1 + 210y2      ! purchase costs
-170w1 - 150w2-36w3-10w4 ! revenues
s.t.
x1+x2+x3        <=500      ! total land available
3.0x1+y1-w1     >=200      ! wheat
3.6x2   +y2-w2  >=240      ! corn
w3 + w4-24x3    <=0        ! sugar beets
w3              <=6000     ! 1st part of quota
end