A rotating shaft carries four masses $A,B,C$ and $D$ rigidly attached to it$,$ the mass centers are

at $1\mathrm{.}25,1\mathrm{.}5,1\mathrm{.}625$ and $1\mathrm{.}375cm,$ respectively from the axis of rotation. A$,$ C and D are of mass

$15,10$ and $18Kg$ respectively, the axial distance between A and $B$ is $16cm,$ and that between

$B$ and $C$ is $20cm,$ the eccentricities of A and $C$ are $90$deg. to one another. Find for complete

balance :

a$)$ The axial distance between the planes of revolution of C and D$.$

b$)$ The angles between A$,$ B and D$.$

c$)$ The mass of B$.$