The only reference to slavery is in the 13th Amendment. You want to repeal that?
Oh Lord, do I have to spell it out?
In the US Constitution, the Three-fifths Compromise is part of Article 1, Section 2, Clause 3:Representatives and direct Taxes shall be apportioned among the several States which may be included within this Union, according to their respective Numbers, which shall be determined by adding to the whole Number of free Persons, including those bound to Service for a Term of Years, and excluding Indians not taxed, three fifths of all other Persons."