Final answer:
The delegates made the Three-Fifths Compromise concerning slavery, which determined how enslaved people would be counted for representation and taxation purposes.
Step-by-step explanation:
The compromise made by the delegates concerning slavery was known as the Three-Fifths Compromise. This compromise settled the controversy over how enslaved people would be counted for representation and taxation. Most Southern representatives wanted enslaved people counted for representation but not for taxation, while the Northern states wanted the opposite. The Three-Fifths Compromise stated that slaves would be counted as three-fifths of a person both for representation and taxation purposes.