use warnings;
use strict;

use feature 'say';

my ($min, $max) = (0, 255);
my ($new_min, $new_max) = (0, 100);

for my $tap ($min .. $max){
    my $x = (($tap - $min) * ($new_max - $new_min) / ($max - $min));
    say "$tap: $x";
}