So I've already found/ was given the radius, hanging mass, and acceleration for three objects but I need to find the moment of inertia using all those three. What equation do I use or how do I incorporate all of them to find the moment of inertia?

3 answers

If they are spinning about the same axis, add them.
Add the accel+radius+ mass? I was a little unclear I need the moment of inertia for each individual object. Does what you said still apply?
Goodness. If they are spinning about the same axis, add the three moments of inertia to get the total moment of inertia.

Now each one individually,
torque=momentinertia*acceleration
force*distance=momentinertia*acceleration
solve for moment of inertia.

I am a little confused what you are given. If the object is hanging, and weight is the force, remember you have to factor in the angle between the force and the motion. See https://wiki.brown.edu/confluence/display/PhysicsLabs/LAB+6+-+OSCILLATORY+MOTION