select R.*, CAST(NVL(Expended,0) as I) as expended from rta_elements R LEFT JOIN
(   select  sum(amount) as Expended, val(substr(sponsor_id,5,2))  as GroupID ;
from tip ;
inner join ledger on ledger.tip_id = tip.tip_id and source="RTA" ;
group by 2) MyAmount ON R.ElementNum = myAmount.GroupID