Or as a slight variation on BrowserUk's code:

use Modern::Perl;
use Data::Dumper;
my @a = ([2,4],[4,5],[8,6],[10,7]);
my @b;
push @b, $_->[1] for @a;
print Dumper \@b;
[download]

prints:

$VAR1 = [
          4,
          5,
          6,
          7
        ];
[download]