Final answer:
Before the new government established by the Declaration of Independence, the US faced issues of taxation without representation, lack of self-government, and violation of individual rights. The new government addressed these issues through the establishment of a representative democracy, a republican system, and the inclusion of the Bill of Rights.
Step-by-step explanation:
The three most significant issues faced by the United States before the establishment of the new government outlined in the Declaration of Independence were taxation without representation, lack of self-government, and violation of individual rights by the British monarchy.
With the new government, these issues were addressed and solved. The concept of "no taxation without representation" led to the development of a representative democracy in which citizens could elect their own representatives to make decisions on taxation.
The idea of self-government was incorporated into the new government system, which established a republic where power was derived from the consent of the governed. The new government also recognized and protected individual rights through the inclusion of the Bill of Rights in the Constitution.