Okay, well the approach I would take is to create a new hash where the keys/values of your existing hash are reversed.

You simply iterate through you existing hash and build up the new hash as you go, like so:

foreach my $key (keys %hash) {
    $newhash{$hash{$key}} += $key;
}
[download]

Using your sample data, that will give you something that looks like:

%newhash = (
             '1' => 40,
             '2' => 60
           );
[download]

Does this help?

Cheers,
Darren :)