$ perl -Mstrict -Mwarnings -e '
my @ranges = qw{15 28-31 3-4 40 17-19};
my ($total_min, $total_max);
s{^(\d+)-?(\d*)$}{$total_min += $1; $total_max += $2 ? $2 : $1}e for @ranges;
print "total is between $total_min and $total_max\n";
'
total is between 103 and 109