It's a reference to the law which was made that slaves would count for 3/5ths of a person when tallying population for representation in the legislative branch of the new American government.
The thirteenth amendment.
The three-fifths clause provided for counting three-fifths of all slaves for purposes of representation in Congress.
citizens
I believe it refers to slaves.
minus three fifths
Assuming that you mean "fifths", the answer is three fifths.
six and three fifths
Three fifths of a hundred is sixty.
two fifths
Three fifths of fifty is 30.
the south were very complex in their organizing
Three fifths is larger than three eighths