Thevenin Equivalent Circuit
You need to consider the sources separately, one at a time, and then combine (add together) their effects to determine the final result.

For example, when considering the 16V source (reference designators would be helpful here), replace the current source with an open circuit. What is the Thevenin equivalent now?

Next add the current source back in. What kind of offset does this introduce into the Thevenin equivalent resistance?