use strict;
use warnings;

my @ages;
while (<DATA>) {
    chomp; push @ages, (split /[, ]+/)[1];
}
print join "\n", sort {$b <=> $a} @ages;

__DATA__
Charley, 34 
Sam, 3 
Lucy, 18 

##</code><code>##

use strict;
use warnings;

my @ages;
while (<DATA>) {
    chomp; push @ages, [split /[, ]+/];
}
for (sort {@$b[1] <=> @$a[1]} @ages) {
    print join (', ', @$_) . "\n";
}

__DATA__
Charley, 34 
Sam, 3 
Lucy, 18