As the delegates debated the Constitution,they also asked questions. Would the new government take all of the power away from all the states? The government didn't take the powers because some powers such as passing tax laws,are shared between the state and National governments the legislative branch makes laws and establishes taxes and can reject vetoes.
The powers of national government makes laws about trade with foreign nations they can set up a military and can set up postal service. The executive branch can carry out laws and command the armed forces.
the Judicial branch interprets laws and decides if laws follow the constitution and can overturn president's actions if these actions go against the constitution and can stop laws that go against the constitution.