TeeEm's practice paper vector help

When doing one of the papers (paper u) from his website I came across this vector question.


Now I don't really follow the last step where he equated (-2,2,-4) to the original question's (2,-2,4). Is there an identity of something I'm missing?

Looks like he made a minor slip.

Should have beeen $w=-\mu+2$ in prior working to flip the direction vector around.

So, eventually, $\lambda = -2\mu+4$



@TeeEm FYI.