A slave is a person that belongs to another one and is treated as property. Serfs, I'm not so sure about this now, were renting the land out from the landowners.
The Declaration of Independence was written so that those who couldn't get formal schooling could read and understand what it was saying.It was written for the average person of that time to be able to comprehend.
I read 1989 instead of 1889 when I answered this question I'm really sorry about that
Answer:
Machines needed to be repaired less frequently. Products could be manufactured on an assembly line.
