Answer
$z=28$
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 $b \cdot c$.
$16*35=z*20$
$560=20z$
$560\div20=20z\div20$
$z=28$