Answer
Use the second and then the first Property of Proportions to rewrite the equation.
Work Step by Step
You are given $\frac{3}{4}$=$\frac{12}{16}$
The second Property of Proportions states that $\frac{a}{b}$=$\frac{c}{d}$ is equivilant to $\frac{a}{c}$=$\frac{b}{d}$
You now know that the proportion can be written as $\frac{3}{12}$=$\frac{4}{16}$.
The first Property of Proportion states $\frac{a}{b}$=$\frac{c}{d}$ is equivalent to $\frac{b}{a}$=$\frac{d}{c}$
So now you can rewrite the proportion as $\frac{12}{3}$=$\frac{16}{4}$
