function FractionCommonDenominator(a, b: integer): integer;
var z: integer;
begin
   if a>b then
   begin
      z:=a;
      a:=b;
      b:=z;
   end;
   Result:=b;
   while Result mod a<>0 do
      Result:=Result+b;
end;

function FractionAdding(a1, b1, a2, b2: integer; var a, b: integer): real;
var i, m: integer;
begin
   b:=FractionCommonDenominator(b1, b2);
   a1:=b div b1 * a1;
   a2:=b div b2 * a2;
   a:=a1+a2;
   if a<b then
      m:=Abs(a) else
      m:=Abs(b);
   for i:=m downto 2 do
      if (a mod i = 0) and (b mod i = 0) then
      begin
         a:=a div i;
         b:=b div i;
         Break;
      end;
   Result:=a/b;
end;