! Beale (Gass & V.)
max -0.75x1 +150x2 -0.02x3 +6x4

st
a) 0.25x1-60x2 -0.04x3 +9x4<0
b) 0.5x1 -90x2 -0.02x3 +3x4<0
c) x3<1
end