use List::BinarySearch qw/ binsearch /;

my @domain = ( 100 .. 1000 );

print "Target: ", $domain[ binsearch { comparator( $a, $b ) } 80, @domain ], "\n";


sub comparator {
  my( $low, $high ) = derive($b);
  return -1 if $a < $low;
  return  1 if $a > $high;
  return 0;
}

sub derive {
  my $raw = shift;
  my $low = $raw * .14;
  my $high = $raw * .19;
  return ( $low, $high );
}
__END__
__OUTPUT__
422