set OBJECT;
param weight{i in OBJECT};
param volume{i in OBJECT};
param weight_limit;
param volume_limit;
param availability{i in OBJECT};
param value{i in OBJECT};
var quantity{i in OBJECT}, integer, >= 0;
maximize total_value: sum{i in OBJECT} quantity[i]*value[i];
s.t. weight_constraint: sum{i in OBJECT} weight[i]*quantity[i] <= weight_limit;
s.t. volume_constraint: sum{i in OBJECT} volume[i]*quantity[i] <= volume_limit;
s.t. availability_constraints {i in OBJECT}: quantity[i] <= availability[i];

data;
set OBJECT := a b c;
param weight := a 16 b 4 c 6;
param volume := a 3 b 4 c 3;
param weight_limit := 30;
param volume_limit := 20;
param availability:= a 3 b 4 c 1;
param value:= a 11 b 4 c 9;
end;