Angular Momentum Problem of turntable

[viper930]

This seems pretty basic but I am drawing a blank. Thanks in advance.

"A cat is sitting on the rim of a wooden turntable that is free to turn about a vertical axis. The turntable's mass is 3 times the cat's mass and is initially at rest. The cat then starts walking around the rim at a speed of 0.6m/s relative to the ground. How fast does the turntable's rim move relative to the ground?"

 

[Chi Meson]

conservation of angular momentum. Just like linear momentum, when two things push apart, mv of one object equals -mv of the other, in angular momentum, the Iw of one equals the -Iw of the other.