Problem $4($Halliday Problem $11\mathrm{.}37)$

In Fig. $11-44,$ three particles of mass $m=23g$ are fastened to three rods of length $d=12cm$ and negligible mass. The rigid assembly rotates around point $O$ at the angular speed $=0\mathrm{.}85ra\frac{d}{s}.$ About $O,$ what are $($a$)$ the rotational inertia of the assembly, $($b$)$ the magnitude of the angular momentum of the middle particle, and $($c$)$ the magnitude of the angular momentum of the assembly?