A Twin Paradox Question, totally lost.

[Engineergirl2]

Homework Statement

Planet W is 12ly from earth. Anna and Bob are both 20 years old. Anna travels to planet W at 0.6c, quickly turns around, and returns to Earth at 0.6c. How old will Anna and Bob be when Anna gets back?

Homework Equations

The Attempt at a Solution

I've tried so many things and nothing is working. Apparently Bob is 60 years and Anna is 52 years. I'm completely lost on the idea of twin paradoxes, I could use some serious help. Thank you!

 

[voko]

Can you see why it is 60 years for Bob?

For Anna, the distance to W and back is Lorentz-contracted.

 

[Engineergirl2]

B/c 24cyrs/0.6c is equal to forty. Therefore you add them and get 60. Then, Anna is 52 years because the total distance that she appears to travel is 19.2? And 19.2cyrs/0.6c is equal to 32. add that to20 and you get 52. I ended up using length contraction. Sorry that was actually pretty easy!