First name the material, then the writing system. Read each recorded action separately. A receipt and a dispatch are movements, not a complete inventory unless starting stock and all other movements are known. Look for independent evidence instead of counting a copied statement twice.
Worked example
In a different invented account, 6 baskets arrive and 2 leave. The difference is 4. If 3 baskets were already there, the final stock could be 7. The two movements alone do not establish the final stock.
Two Invented Storehouse Notes
Historical background: clay tablets often carried cuneiform, a wedge-shaped writing system used for different languages. The following English notes are invented practice records, not translations of ancient tablets. Note A says 8 jars arrived on Monday. Note B says 3 jars left on Tuesday. The starting stock, other movements, writer and number of people who could write are unknown. A later card copies Note A word for word; it supplies no separate observation.