King Saud University GAMS Code Binary Variable & Free Variable Worksheet

check the GAMS code if it is correct and show me the result also fix it if there are any mistakes

sets i/1*40/, g/1*4/;
alias (i,j)
parameters a(i)/1 210,2 385,3 270,4 175,5 200,6 190,7 160,8 410,9 295,10 160,11 360,12
150,13 235,14 315,15 340,16 260,17 275,18 185,19 290,20 220,21 680,22 1240,23 1680,24
1090,25 2100,26 1950,27 2821,28 1730,29 1450,30 860,31 525,32 265,33 300,34 870,35
600,36 450,37 220,38 485,32 230/,
s(g)/1 7000,2 7000,3 7000,4 7000/;
scalar delta;
delta = 14;
free variable y(i);
positive variable d(i,j);
binary variable x(i,g);
free variable z;
equations con1(i),con2(g),con3(i),con4(i,j),con5(i,j),con6(g),con7,con8(g),con9,obj;
con1(i).. sum(g,x(i,g)) =e= 1;
con2(g).. sum(i,(a(i)*x(i,g))) =l= s(g);
con3(i).. y(i) =e= sum(g,ord(g)*x(i,g));
con4(i,j)$(ord(i) ne ord(j))..d(i,j) =g= delta*(y(i)-y(j));
con5(i,j)$(ord(i) ne ord(j))..d(i,j) =g= delta*(y(j)-y(i));
con6(g).. x(’21’,g)+x(’22’,g)+x(’23’,g)+x(’24’,g)+x(’25’,g)+x(’26’,g)+x(’27’,g)+x(’28’,g)+x(’29’,g)
=e= 9;
con7.. x(‘4′,1)+x(’10’,1) =l= 1;
con8(g).. x(’13’,g)+x(’24’,g) =l= 1;
con9.. x(‘9′,2)-x(’13’,2) =e= 0;
obj.. z =e= sum((i,j)$(ord(i) ne ord(j)), d(i,j));
model floor_assign_mdl/
con1,
con2,
con3,
con4,
con5,
con7,
con8,
con9,
obj/;
option mip = cplex;
solve floor_assign_mdl using mip minimizing z;
display x.l ;