Answer:
The biggest weakness of a barter system is there must be an exchange rate for each and every good traded. e.g.: in an economy with only three goods, ducks, chickens and potatoes, you must readily know all of the following rates to conduct business. 1 duck=2 chickens, 1 chicken=3 potatoes, 1 duck=6 potatoes, 1 potato=1/3 chicken or 1/6 duck.... etc. If more good are added the list goes on and on.