data1R.fa
data2P.fa
data2R.fa
data2P.fa #say each of this file contain lines of numbers
....      #and there are 40 of files

##</code><code>##

perl mycode.pl data1R.fa data1P.fa 
perl mycode.pl data2R.fa data2P.fa 

##</code><code>##

use warnings;
use strict;

my $file_r = $ARGV[0];
my $file_r = $ARGV[1];
open FILE_R, "< $file_r" or die "Can't open $file_r : $!";
open FILE_P, "< $file_p" or die "Can't open $file_p : $!";

my @rdata;
my @pdata; #these two are of the same size

while (<FILE_R>){
  chomp;
  push @rdata, $_;
}

while (<FILE_P>){
  chomp;
  push @pdata, $_;
}

my @sum = map {$rdata[$_] + $pdata[$_]} 0..$#pdata;
 
print "$file_r\n";
print ">\n";

foreach my $sum (@sum){

 print "$sum\n";
}

##</code><code>##

>data1
sum_of_elements from data1R.fa and data1P.fa
>data2
sum_of_elements from data2R.fa and data2P.fa