Simple questions about current flow and superposition
+1 for showing all your work, that's excellent.  -0.01 for the low contrast -- I did have to squint a bit, but it was worth it.

The intuitive way to figure out the sign of the voltage contributions of each source is to start at the '+' sign on a voltage source, or the point of the arrow on a current source, and trace through your \$V_x\$.  If your finger hits '+' and then '-', it's a positive contribution; if your finger hits '-' and then '+', it's negative.

The dreadfully formal way is to label all the nodes or draw in the currents and then do nodal or mesh analysis.