A shaft consisting four masses A, B, C and D is in complete balance. The masses A, C and D are 20 kg. 12 kg and 10 kg respectively. The radii of rotations of masses A, B, C and D are 12 cm, 15 cm, 17 cm and 20 cm respectively. The planes of rotation of A and B are 20 cm apart whereas those of B and C are 25 cm apart. The angle between the radii of A and C is 90o. Determine mass at plane B and distance between the planes of C and D.