You give the Party class a method that looks for a red table:

sub has_red_table {
    my $self = shift;
    for (@{ $self->tables }) {
        return 1 if $_->color eq 'red';
    }
    return 0;
}
[download]

Also, note that you have a serious typo: "table" is not "tables" ... but Moose should catch that for you. Here is the client that i used to help you as well:

use strict;
use warnings;

my $table1 = Table->new(size => 'big', color => 'red');
my $table2 = Table->new(size => 'small', color => 'blue');

my $party1 = Party->new( tables => [$table1,$table2] );
my $party2 = Party->new( tables => [$table2,$table2] );

print $party1->has_red_table, $/;
print $party2->has_red_table, $/;
[download]

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)