Question

once the delegate settled the three-fifths compromise, what issue did they tackle next

Answer 1

After settling three-fifths compromise, they tackled the electoral process for the residency.   This decision was taken at the constitutional convention by the delegates.   The delegates proved that each of the states had a different agenda and separate set of interests.   The delegates also forwarded the idea of amending the articles of confederation which defines functions of the US government.

Answer 2

Once the delegates determined the Three-Fifths compromise, then they tackled the electoral process of the presidency.

This was one of the major compromises in the constitutional convention in between the small states and bug states as such.

All the three-fifths compromise delegates went ahead and discussed the electoral process.