Atwoods machine, solve for mass

[aaronszone1]

Homework Statement

A simple Atwood's machine uses two masses, m1 and m2. Starting from rest, the speed of the two masses is 3.0 m/s at the end of 3.0 s. At that instant, the kinetic energy of the system is 60 J and each mass has moved a distance of 4.5 m. Determine the values of m1 and m2.

Homework Equations

The equation I know that must be used is K=.5mv^2 where K is kinetic energy, m is mass, and v is velocity.
But I'm having a hard time finding another equation to solve for the masses.

The Attempt at a Solution

Sorry if the pictures are hard to see my writing in. I tried to edit them so my writing was easier to see.

 

[jbsteele]

I started by multiplying the equation K=.5mv^2 by 2, so I can solve for m instead of v. I then plugged in the given values to get m1 + m2= 60/9. Then I tried to use the distances and the time given to solve for the acceleration. I used a=d/t and got a= 4.5/3. Then I tried to use the acceleration and the velocity to solve for m1 and m2. I used v=at and got m1 + m2 = 9/8a.I then tried to substitute the equations m1 + m2 = 60/9 and m1 + m2 = 9/8a to solve for m1 and m2 but I'm still stuck. I'm thinking there has to be another equation I'm missing but I'm not sure what it is. Any help would be greatly appreciated. Thank you!