let us take that the current in the first branch to the left is w and then x and then y and then to the right is z then we can
   write that
   w + x + z = y
   then to get the currents we apply the kirchoffs voltage law so that we get
   - 200 w - 40.0 + 80.0 x = 0
   - 80.0 x + 40.0 + 360 - 20.0 y = 0 
   + 360 - 20.0 y - 70.0 z + 80.0 = 0
   so use the above equations to get the currents x, y, z and w
   then the voltage across 20.0 Ω resistor will be
   V_{80.0 Ω} = I R
               = y 80.0 Ω
               = .......... V