Find acceleration of a modified atwood machine

[sunniexdayzz]

Homework Statement

An Atwood machine is constructed using a disk of mass 2.4 and radius 23.4. What is the acceleration of the system? The acceleration of gravity is 9.8 .
Picture: http://img.photobucket.com/albums/v356/SfTbLxMiShi/atwood.jpg

Homework Equations

$$\sumF=ma$$
torque = I(alpha)

The Attempt at a Solution

i tried to find the sum of the forces in the y direction for the 3 different bodies, then i tried to find the torque for the pulley and use one of the bodies' force and set it equal to the torque

 

[rock.freak667]

Convert all the masses to weights, then find the resultant moment about the disk (the resultant of 1.66 and 1.28). Then use Torque=I*alpha