Final answer:
A transaction is distinguished as barter when goods or services are directly swapped without money, while a sale involves money as an intermediary. Money's function as a medium of exchange and store of value facilitates more complex and future-focused transactions.
Step-by-step explanation:
To distinguish a transaction as a barter or a sale when it is partially both, we need to look at the nature of the exchange. In a barter, goods or services are swapped directly without the use of money as an intermediary. When money is involved, even if only partially, it typically signifies a sale transaction. For example, if one trader's goods are valued at 50 units and another's at 10 units, using money to balance the exchange turns it into two separate sale transactions. However, if these transactions involve future commitments of exchange, such as a farmer wanting to acquire a tractor in six months with strawberries, it complicates the barter system. Money, serving as a medium of exchange and a store of value, helps overcome these issues by acting as an intermediary and preserving value over time, facilitating the growth of economies and allowing better planning and future contracts.