## Prealgebra (7th Edition)

$\frac{6}{8} = \frac{9}{12}$ True
x is to y is the same as $\frac{x}{y}$ 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 $b \cdot c$. Six is to eight as nine is to twelve is the same as $\frac{6}{8} = \frac{9}{12}$ This proportion is true because $6*12=9*8=72$