The better way is to use a hash. You already know how to do it, just create another hash alongside %var_list (which could be better named %questions):

my %questions = (date_in  => 'Start Date',
                 date_out => 'End Date',
);
my %answers;
for my $key (keys %questions) {
    $answers{$key} = prompt($questions{$key} . ': ');
}
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Alternatively, you can store all the information in one hash:

my %questions = (date_in  => { q => 'Start Date' },
                 date_out => { q => 'End Date' },
);
for my $key (keys %questions) {
    $questions{$key}{a} = prompt($questions{$key}{q} . ': ');
}
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
[download]