#!/usr/bin/perl

my $input = 'input.txt';
my $output = 'output.txt';
my $constant = 15; #number you are multiplying by

open FILE, "<", $input;
chomp(my @array=<FILE>);
close FILE;

for(@array) {
	if ($_ > 20) {
		open OUTPUT, ">>", $output;
		print OUTPUT ($_ * $constant)."\n";
		close OUTPUT;
	}
}