Sorry if I may ask an idiot question, but its gonna be for few hours right now I have spent on this question.
I am asked to find out the value of the voltage between points A and B, aka Uab, and I am supposed to use the Thevin equivalent.
I found 12.4 ohms for the thevenin resistance, but for that I replaced every sources by the equivalent, and that short circuited the 4ohms resistance on the left, cause of the replaced 20v voltage source. But when it comes to the Thevenin voltage, I dont know what to do, the 2 resistances above are bothering me, do I need to use the Kennely theorem?

Thanks in advance!![enter image description here](https://i.stack.imgur.com/qXAJ5.jpg)