I think this is what you want. It produces your (updated, I was scratching my head at first :-) desired output. However, you imply that the text files, particularly for %hashA are already sorted. Perhaps you should consider changing the hash for a list so that the order is preserved as you read the data in.

use strict;
use warnings;

my %hashA =
   (
      'accord newton second' => 80,    
      'acceler smaller greater' => 78,
      'addit law motion' => 56,
      'meant bodi act forc'=> 55,
   );
my %hashB =
   (
      2 => 'addit law motion',
      3 => 'accord newton second',
      4 => 'meant bodi act forc',
      5 => 'acceler smaller greater',
   );
my %hashC =
   (
      2 => "In addition to ",
      3 => "According to Newton",
      4 => "It also meant that whenever ",
      5 => "The acceleration is",
   );

my @insertionOrderA =
   sort {$hashA{$b} <=> $hashA{$a}}
   keys %hashA;

my %reversehashB = reverse %hashB;

foreach (@insertionOrderA)
{
    print "$reversehashB{$_} $hashC{$reversehashB{$_}}\n";
}
[download]

I hope this is of use.

Cheers,

JohnGG