Given the following linear programming model:
minimize Z=8.2x1+7.0x2+6.5x3+9.0x4
subject to
6x1+2x2+5x3+7x4
>= 820
x1/(x1+x2+x3+x4)
>= 0.3
(x2+x3)/(x1+x4)
<= 0.2
x3
>= x1+x4
x1,x2,x3,x4
>=0
transform the model into standard form and solve by using the computer (solver)