Does anyone have any idea how to solve this?
I've redrawn it to make it easier to solve. now there is just a bunch of resistors in a clear series or parrellel circuit, 

To solve it linearly, you can begin by working out what the resistance of 8K and all that is in parrellel is, once you know that, you know the voltage at the first node and can work down the tree until your left with your Vo

E.g. 2K + 4K on the right = 6K, that 6K in parrellel with 6K = 3K, that 3K in series with 3K = 6K, 3K in parrellel with 12K and so on, you then know the voltage of that node, and can then divide the next node by there relative resistances until you finally reach your Vo