Find the checking balance of the accounts whose savings balance is higher than the average savings balance.
select t2.balance from accounts as t1 join checking as t2 on t1.custid = t2.custid where t1.name in (select t1.name from accounts as t1 join savings as t2 on t1.custid = t2.custid where t2.balance > (select avg(balance) from savings))