1. The problem statement, all variables and given/known data Determine the value of the voltage Vx across the 3A current source. 2. Relevant equations 3. The attempt at a solution I am really confused about how to do it. What I thought of is to find the voltage across the 4 ohm resistance which is 12 V. I though of subtracting that from the power sources. But I am not sure which power source should be positive and which one should be negative? Should I just assume the bigger 6V to be positive just because it is the bigger power source? I might be completely wrong on this one. So please help me. This is not really a homework problem, this is in one of my practice tests, so I would appreciate any proper explanation I can get, rather than vague hints. Thank you.