How can find the voltages at 2 nodes with 1 equations and 2 variables?
You have too much variables and arrows (not wrong, but unnecessary). I redrawed the circuit:



You obviously missed that the voltage over R4 can be expressed in terms of Vx. This is Kirchoffs voltage law.

I have written the current equations for nodes 1 and 2. There are 2 unknowns and 2 equations. 

Hopefully clear now.