\Dat Oil
\xij: raw oil type i refined to oil type j
\yi: raw oil sold unrefined.

\ Ignore the cost of buying raw oil, since it pays of to buy all

max 5.15 x11 + 5.15 x21 + 5.15 x31 + 5.15 x41 
+ 3.95 x12 + 3.95 x22 + 3.95 x32 + 3.95 x42
+ 2.99 x13 + 2.99 x23 + 2.99 x33 + 2.99 x43
+ 1.85 y1 + 1.85 y2 + 2.95 y3 + 2.95 y4  

st
x11+x12+x13+y1=4000
x21+x22+x23+y2=5050
x31+x32+x33+y3=7100
x41+x42+x43+y4=4300

\95
\68 x11 + 86 x21 + 91 x31 + 99 x41 = 95 x11 + 95 x21 + 95 x31 95 x41
27 x11 + 9 x21 + 4 x31 -4 x41 = 0

\90
22 x12 + 4 x22 - 1 x32 -9 x42 = 0

\85
17 x13 - 1 x23 - 6 x33 -14 x43 = 0

x11+x21+x31+x41 <= 10000
x13+x23+x33+x43 >= 15000

bounds

integer

end