I am having a hard time trying to determine the voltage at VA and VB. I know that VC = VD = 10V. At first I thought this would be a simple setup, but I'm unsure about how to set up an equation for VA considering that there is a resistor and a voltage source between it and the reference node. I've built this circuit and made measurements with a DMM, I'm just trying to come to the same results using nodal analysis. Can anyone point me in the right direction?