Mountain Community Bank: Mountain Community Bank (MCB) runs a multiuser DBMS on a LAN file server. Unfortunately, at the present time, the DBMS does not enforce concurrency control. One MCB customer had a savings account balance of $500 when the following three transactions related to this account were processed at the times shown (on the same day): 9:01:02 am -- Cash Withdrawal of $100 9:01:05 am -- Payroll Deposit of $300 9:01:20 am -- Automatic Fee Payment (withdrawal) of $20 Each of the three transactions reads the customer account when the balance was $500 (i.e., before any of the other transactions were completed). The updated customer record was returned to the database in the order shown in the bulleted list above. If concurrency control was used in the DBMS, what would be the correct account balance for the customer immediately after the three transactions have been completed? Enter numeric digit(s) in the nearby box(es); do not use any non-numeric symbol.