what is the moment of inertia of the wheel about its axle???

Question

A wheel with massless spokes has an inner rim at r=1/2R and an outer rim at r=R. Each rim has mass 1/3M. What is the moment of inertia of the wheel about its axle???

Answer 1

Since
I=(1/2)m(R1^2 + R^2)
I=(1/6)M(1/4 R^2 +R^2)

finally
I=(5/24) M R^2

(by the way there is only one rim)