Divide(Math) within a subquery

[Sam Brinley]

select distinct a.error, jny.JAN, fby.FEB, mch.MAR from
(select error, sum(value) JAN from tb_sum where month = '200601' group by error) jny,
(select error, sum(value) FEB from tb_sum where month = '200602' group by error) fby,
(select error, sum(value) MAR from tb_sum where month = '200603' group by error) mch,
tb_sum a
where jny.error = fby.error
and jny.error = mch.error
and jny.error = a.error
group by a.error;

Displays like this...

+-------+------+-------+------+
| error | JAN | FEB | MAR |
+-------+------+-------+------+
| err1 | 376 | 885 | 993 |
| err2 | 6939 | 13287 | 4366 |
| err3 | 5433 | 12401 | 5329 |
| err4 | 365 | 896 | 913 |
| err5 | 496 | 1377 | 1355 |
| err6 | 42 | 89 | 94 |
| err7 | 220 | 489 | 499 |
| err9 | 215 | 585 | 442 |
+-------+------+-------+------+

However I want to divide all of these by another table. For instance the JAN err1 block is 376. I want to divide the 376 (and all else in the jan column) by a value in another table.

select days from tb_month where month = '1';

+------+
| days |
+------+
| 31 |
+------

Any ideas?

Thanks,
Sam