Solving a Thevenin equivalent circuit
Think of a black box that you are told is a Thevenin source.  You take two different pairs of current,voltage measurments.  How would you solve that?

Do you need to know if the inside is made of several sources with a mesh of resistors, or single voltage source with series resistance?  How would you tell the difference between these two cases?

Hint: much of the details of this problem are a distraction to see if you fall for getting lost in the minutia instead of thinking about the whole problem.