proc optmodel;

set Plant = {"P1", "P2"};
set Region = {"R1", "R2", "R3"};

number demand{Region} = [25 95 80];
number capacity{Plant} = [100 125];

number cost{Plant, Region} = [ 
250 325 445
275 260 460
];

var flow{Plant, Region} >= 0;

minimize z = sum{i in Plant, j in Region}flow[i,j]*cost[i,j];

con capacitycon{i in Plant}: sum{j in Region}flow[i,j] <= capacity[i];
con demandcon{j in Region}: sum{i in Plant}flow[i,j] >= demand[j];

solve;
print z flow;
expand;
quit;