A shaft carries four masses A,B,C and D placed in parallel planes, perpendicular to the shaft axis and in the same order along the shaft. The masses of B and C are 36 kg and 25 kg and both are assumed to be concentrated at a radius of 150 mm, while the masses A and D are both at a radius of 200 mm. The angle between the radius of B and C is 1000 and that between B and A is 1900, both angles being measured in the same sense. The planes containing A and B are 250 mm apart and those containing B and C are 500 mm apart. If the shaft is to be in complete dynamic balance, find:

a. The masses of A and D.

b. The distance between planes C and D

c. The angular position of mass D.