Answer
$$16.0$$
Work Step by Step
The distance $d$ between the two points $(x_{1},y_{1})$ and $(x_{2},y_{2})$ is given by
$$d=\sqrt {(x_{2}-x_{1})^{2} + (y_{2}-y_{1})^{2}}.$$
Substitute $x_{1}=-8$, $y_{1}=8$, $x_{2}=8$ and $y_{2}=8$ and round to the nearest tenth.
$$d=\sqrt {(8-(-8))^{2}+(8-8)^{2}}=\sqrt {256+0}=\sqrt{256}=16.0$$