What is one problem that might commonly occur when one is bartering?

The one problem that commonly occurs when bartering is the exchange of a valuable item to a less valuable item.

Explanation

Bartering is a system of trading one product in exchange for another.

Hence, the person who needs a certain item depended on another who is ready to sell the same.

Bartering doesn't involve money transactions.  

For example, a woodcutter giving wood to a farmer in return for wheat.

But this system had many disadvantages like lack of need, double coincidence of needs, deferred payments etc.

john locke and voltaire

a.indigo and cochineal

b.animal hides

c.silver and gold

e.cacao beans and sugarcane