Finding Coordinates on a 3D vector My question is how to find the coordinates for a point on segment $KL$ where 
$K=(3,2,1)$ and $L=(7,9,5)$ that is $5$ units away from $K$.
I know that the vector is $KL=[4,7,4]$ and the length of the entire vector is $9$ but not sure how to move the point along the vector by $5$ units

We want to move $\dfrac 59$ of the vector $[4,7,4]$, which is $\left[2\frac29, 3\frac89,2\frac29\right]$
This equates to the point 
\begin{align}P&=K+\frac 59(KL)\\
&=(3,2,1)+\frac59[4,7,4]\\
&=(3,2,1)+\left[2\frac29, 3\frac89,2\frac29\right]\\
&=\left(5\frac 29,5\frac89,3\frac29\right)\\
&\approx (5.22, 5.89, 3.22)\quad(2\text{d.p.})\end{align}
