Here's my version:

#!/usr/bin/perl -l
use strict;
use warnings;

my @arr1 = qw(john:::10 bill:::9 mary:::35 willy:::21);
my @arr2 = qw(10 9 35 21);

my %map = map {$arr1[$_]=>$arr2[$_]} (0 .. $#arr1);
@arr1 = sort{$map{$a}<=>$map{$b}} keys %map;

print join("\n",@arr1);

__END__
bill:::9
john:::10
willy:::21
mary:::35
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