Help with superposition question
Let´s start taking the current source outta the circuit and defining a parameter: I1= current through dependent source

Done that let´s get into it. 

With the current source out we have 2 equations:

Vx- (Vo-Vx)/2 + I1 =0

and
I1 + ( -Vo/2 - (Vo-Vx)/2 - (Vo+4)/2 =0

Note that equations have been found using nodal analysis in the circuit nodes.

Equal equations and I1 is canceled out.
We also know by KVL that Vx + 2Vx = 4 + Vo
Now 2 equations, 2 variables, Vo(the first Vo with current source out) can be found and its value is Vo(1) = -20/8

Now for the Second part, without the 4V Source:
Again labelling I1 as the same thing, and doind the same analysis we have the equations:

I1 = (Vo-Vx)/2- Vx + 6 and

I1 = Vo + (Vo-Vx)/2  and finally
3Vx = Vo

Solving it for Vo(second Vo now) we have Vo = 18/4

Now, summing both Vo´s we get Vo = -20/8 + 18/4 = 2