! Bronson: 1.7, p 6; 4.7, p 40
! z* = $125 000, x(1..4) = 37 727, 12 273, 2273, 2727
  MAX 4 x1 - 3 x2 + 6 x3 -  x4
SUBJECT TO
maxreg)     x1 + x2 <= 100000
maxpre)     x3 + x4 <= 20000
domest)     x1 + x3 <= 40000
foreign)    x2 + x4 <= 60000
octanreg)   x1 -10 x2 <= 0
octanpre) 6 x3 -5 x4 <= 0
vpresreg) 2 x1 -8 x2 <= 0
vprespre) 2 x3 -8 x4 <= 0
minreg)     x1 +  x2 >= 50000
minpre)     x3 +  x4 >= 5000
! Just for us:
regular)    x1 + x2 - regular = 0
premium)    x3 + x4 - premium = 0
END