Answer
$r_{z}=-2.8$ m
Work Step by Step
if $\overrightarrow {r}$ is the sum of two vectors $\overrightarrow {r}=\overrightarrow {c}+\overrightarrow {d}$,
then $\Rightarrow$
$ r_{x}=c_x+d_x;$
$r_y=c_y+d_y;$
$r_{z}=c_{z}+d_{z}$
So we get,
$r_{z}=c_{z}+d_{z}=(-6.1)+(3.3)=-2.8$ m
