I am still perplexed as to what you actually are trying to do. So, I have modified your code to the following:

#!perl

use strict;
use warnings;

my( $k, $i, $j ) = ( 0, 0, 0 );

until($k==2){
  # @averages[$k]=int((@scores[$i][$j]+@scores[$i][$j+1]+@scores[$i][$
+j+2]+@scores[$i][$j+3])/3);
  print "AVERAGE [$k] = (scores[$i][$j] + scores[$i][".($j+1);
  print "] + scores[$i][".($j+2);
  print "] + scores[$i][".($j+3);
  print "]) /3)\n";
  $i++;
  $j++;
  $k++;
}
[download]

Now, it isn't very pretty, but it takes your snippet, makes it work, and produces some debug info to match against your desired result.

> perl test.pl
AVERAGE [0] = (scores[0][0] + scores[0][1] + scores[0][2] + scores[0][
+3]) /3)
AVERAGE [1] = (scores[1][1] + scores[1][2] + scores[1][3] + scores[1][
+4]) /3)
[download]

Is this really what you wanted?