Need Help, dont understand

The wheels of a wagon can be approximated as the combination of a thin outer hoop of radius r, = 0.474 m and mass 4.32 kg, and two thin crossed rods of mass 7.37 kg each. Imagine replacing the wagon wheels with uniform disks that are tg = 4.62 cm thick, made out of a material with a density 5990 kg/m?>. If the new wheel is to have the same moment of inertia about its center as the old wheel about its center, what should the radius ry of the disk be? Fq = 0.3551 Incorrect