We have the three KVL for the 3 loops:
8 = - 125*(i1 + i0) + 250*(i2 – i0)
12 = 500*i1 + 125*(i0 + i1)
12 = 250*(i3 – i0) + 500*i3
We have 3 equations for 3 unknowns thus we can solve the system.
We get i0 = - 0.024 A
i1 = 0.024 A
i2 = 0.008 A
So finally we get Va = R*i2 = 500*i2 = 4 V