Find a terminal point $Q$ of a nonzero vector $\mathbf{u}=\overrightarrow{P Q}$ with initial point $P(-1,3,-5)$ and such that (a) $\mathbf{u}$ has the same direction as $\mathbf{v}=(6,7,-3)$. (b) $\mathbf{u}$ is oppositely directed to $\mathbf{v}=(6,7,-3)$.