How to find voltage in this circuit by superposition
When SW1 is in left position, Effect of both sources are there, I = 0.1 A. When SW2 is in right position, only the effect of E1 is there, I = 0.15 A. Also suppose SW1 is in the left postion and E2 is shorted, the resulting circuit is exactly the same as when SW2 in right position. It means the effect of E1 is again I = 0.15 A. Since the combined effect = 0.1 A for switch in left position, we can conclude that the effect of E2 is I = 0.1 - 0.15 = -0.05 A. If we assumed the direction of current to be +ve, if it flows from right to left of the ammeter, -0.05 A means the current is just in the opposite direction.i.e, from left to right of the ammeter. Now all left is to solve the resulting circuit using simple KVL or KCL.