Before the invention of money, people satisfied their needs through barter trades, where goods were exchanged between two parties who would want one another's things.
- As shown in the top image, a fisherman would like to exchange his fish for some vegetables from a farmer, and they agreed on a barter trade of 2 fish for 3 cabbages.
- Then a farmer would like to exchange his cabbages for some soaps from a soap maker, and they agreed to trade 5 cabbages for 4 soaps.
- Now if the soap maker would like to trade her 2 soaps and 2 cabbages for some fish from the fisherman, according to this barter, how many fish would the fisherman give her?