Chapter 7 - Problem 7. 22, p330 Whitlock Department Stores runs a multi user DBMS ON a LAN file server. Unfortunately, at the present tale ole
DBMS does not enforce concurrency control Onc Whitlock customer had a balance due of $500
when the following three transactions related to this customer were
processed at about the same time:
• Payment of $500
• Purchase on credit of $100
- Merchandise return (credit) of $50

i think the answer is a or d

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