Final answer:
Slaves were counted as three-fifths (3/5) of a person for representation and taxation purposes after the Three-Fifths Compromise at the Constitutional Convention.
Step-by-step explanation:
After much discussion at the Constitutional Convention, it was decided that slaves would count as three-fifths (3/5) of a person in regards to population for both purposes of representation in Congress and federal taxation. This agreement is known as the Three-Fifths Compromise. The issue was a deeply contentious one, with Southern states favoring the inclusion of slaves in population counts to increase their political power, while Northern states were opposed, leading to this fraught compromise. Eventually, this compromise was rendered obsolete with the passage of the 13th Amendment, which abolished slavery, and the second section of the 14th Amendment, which repealed the three-fifths rule.