gplsolver.mod

var x1, binary;
var x2, binary;
var x3, binary;
var x4, binary;

minimize obj: 170 * x1 + 200 * x2 + 50 * x3 + 150 * x4;

s.t. c1: 8 * x1 + 30 - 30 * x1 + 3 * x2 + 10 - 10 * x2 +  7 * x4 + 15 - 15 * x4 <= 50;
s.t. c2: 8 * x1 + 30 - 30 * x1 + 15 * x3 + 25 - 25 * x3 + 7 * x4 + 15 - 15 * x4  <= 50;
s.t. c3: -1000 * x2 - 1000 * x3 + 8 * x1 + 30 - 30 * x1 + 3 * x2 + 10 - 10 * x2 + 15 * x3 + 25 - 25 * x3 + 7 * x4 + 15 - 15 * x4 <= 50;

solve;
display x1, x2, x3, x4;
end;