Answer
See below.
Work Step by Step
The general equation for inverse variation is: $y=\frac{a}{x}$ where $a$ is some constant. Then plugging in the given values for $x,y$ we get: $5=\frac{a}{1}\\a=5$.
Thus the model is: $y=\frac{5}{x}$. Then plugging in $x=-3$: $y=\frac{5}{-3}=-\frac{5}{3}$
