Shows the experimental set up of a meter bridge. The null point is found to be 60 cm away from

Shows the experimental set up of a meter bridge. The null point is found to be 60 cm away from the end A with X and Y in positions as shown. When a resistance of `15 Omega` is connected in series with Y, the null points is found to shift by 10 cm towards the end A of the wire. Find the position of the null point if resistance of `30 Omega` were connected in parallel with Y.