#!/usr/bin/perl
use strict;
use warnings;

my @set = (
{
    'id' => '1462',
    'items' => [
        '9.9',
        '10.1',
        '10.3',
        '10.5',
        '10.8',
        '10.94'
    ],
},
{
    'id' => '1463',
    'items' => [
        '3.1',
        '4.3',
        '4.5',
        '4.6',
        '4.7',
        '4.8'
    ],
}
);


my @aoa;
foreach my $hash_ref (@set) {
    push @aoa, $hash_ref->{items};
}

my $totals = sum_up->(\@aoa);

sub sum_up {
    my $aoa = shift;
    
    my @totals;
    #\@totals would look like this:
    #[
    # '13',
    # '14.4',
    # '14.8',
    # '15.1',
    # '15.5',
    # '15.74'
    #]
    return \@totals;
}