my $a = 2; 
my $b = 3;
print &add($a, $b) . "\n";

my $opt = "$a, $b";
print &add(eval($opt)) . "\n";

my @opt = ($a, $b);
print &add(@opt) . "\n";

exit;

sub add {
   my ($x, $y) = @_;
   return ($x +$y);
}