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 )  ) 
accounts with savings balance higher than average savings balance refers to a subquery comparison WHERE T2.balance > (SELECT AVG(balance) FROM savings); checking balance of these accounts is SELECTed from a JOINed table of accounts and checking based on customer ID;