Answer
$$8.5$$
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 $x_{1}=5$, $y_{1}=4$, $x_{2}=-3$ and $y_{2}=1$ and round to the nearest tenth.
$$d=\sqrt {(-3-5)^{2}+(1-4)^{2}}=\sqrt {64+9}=\sqrt{73}=8.5$$