Only by watering and playing with water can a tree bear a good load.

Maximum 25x3+15y3

0 & lt= x 1+x2+x3 & lt； = 30

0 & lt= y 1+y2+y3 & lt； = 20

20x 1+ 10y 1 & gt； = 30 x2+20 y2 & gt； = 25x 3+ 15y 3 & gt； = 0

matlab:

f =[0 0-25 0 0- 15]；

a =[ 1 1 1 0 0； - 1 - 1 - 1 0 0 0; 0 0 0 1 1 1; 0 0 0 - 1 - 1 - 1;

-20 30 0 - 10 20 0; 0 -30 25 0 -20 15; 0 0 -25 0 0 - 15; ];

b =[30； 0; 20; 0; 0; 0; 0];

Lb = zero (6,1);

& gt& gt[x fval] = linprog(f，A，b，[]，[]，lb)

Optimization terminated.

x =

17.5000

0.0000

12.5000

0.0000

17.5000

2.5000

fval =

-350.0000