#!/usr/bin/perl

use strict;
use warnings;

use Data::Dumper;

my @rows = map {chomp; $_} (<DATA>);
print Dumper \@rows;

my @filtered = grep { $_->[2] == 20 } map { [split /;/, $_] } @rows;
print Dumper \@filtered;

__DATA__
Zeile1;;100;;
Zeile2;;60;;
Zeile3;;20;;
Zeile4;;20;;
Zeile5;;40;;