Answer:
They were usually paid with units of bread and beer.
It seems that your question has missing details, but anyway, I have found the rest of them so hope this answer helps. This statement, <span>"Buyers and sellers can easily buy and sell goods." can be represented by the principle of the American free enterprise system which is COMPETITION. Hope this is the answer that you are looking for.</span>
According to this author, accounts used in making <span>statements of fact must be verified. But it should be noted that this is not the only method in this case. </span>
