Question

How did the principle of federalism resolve the issue of national versus states’ rights ?

Answer 1

Because under federalism, Framers could create a new Central Government that would be strong enough to meet the nations needs and, at the same time, preserve the strength of the existing states.
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Answer 2

Federalism resolves the issues of National versus States rights by giving certain powers to the National government and certain powers to the States governments in a way they coexist without erasing the powers of the other.

To do so, the Constitution has to list the powers of each as implied, exclusive, reserved, inherent, delegated or expressed powers so the Federal government and the State government know their competence.