Prove or Disprove: if the complement of A is a subset of B then A union B= U

This is as far as I got.

The complement of A is anything that is NOT A.

If everything that is NOT A IS a subset of B then that does NOT necessarily mean that A union B=U.

Let x be an element in the complement of set A.

If x E of the complement of set A, and the complement of A is the subset of B then A also must be the subset of B. Because A is the subset of B then A union B= B it is NOT EQUAL to U. However, the complement of B union B would equal the universe.