Hello!
Answer:
To understand why the feudal system was also an economic system, we need to understand what an economic system is.
An economic system is basically a way a society distributes services, goods, resources, etc. in an area.
The feudal system was also considered an economic system because they exchanged land for service or labour. In the feudal system, the monarchs were at the top of the chain, followed by the lords, then the knights, and lastly, the peasants/serfs.