Answer
$n=25$
Work Step by Step
We are trying to solve for the given variable so that the proportion is true.
To determine if a proportion is true, we have to find if the cross products are equal.
The cross products of $\frac{a}{b}=\frac{c}{d}$ are $a \cdot d$ and $b \cdot c$.
$-3.5*n=(-7)*12.5$
$-3.5n=-87.5$
$-3.5n\div-3.5=-87.5\div-3.5$
$n=25$