Solving a Complex Math Problem - Need Help!

[Icetray]

The attempt at a solution

\frac{n2 - n6}{n5 - n6} = \frac{- 18}{30}\frac{-28}{20}

The answer is -30.9 rad/s (clockwise). The problem looks rather simple and I'm really not sure what I'm doing wrong.

Also if anyone knows where I can get more worked examples on these kinds of problems I'd really appreciate it!

Thanks in advance guys! (:

 

[voko]

As in the previous problem, consider the frame co-rotating with arm 6. In this frame, <br /> n_2&#039; = n_2 - n_6<br /> \\ n_5&#039; = n_5 - n_6<br /> Then you can easily relate n_2&#039; and n_5&#039; in this frame, and then convert to n_2, n_5 and n_6.