#### Answer

$z=3.2$

#### 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 $b \cdot c$.
$8*6=z*15$
$48=15z$
$48\div15=15z\div15$
$z=3.2$