1. The problem asks us to find which ratio is equivalent to $7 : 3$. 2. Two ratios $a : b$ and $c : d$ are equivalent if their fractions are equal, i.e., $\frac{a}{b} = \frac{c}{d}$. 3. Let's check each given ratio by simplifying or comparing to $\frac{7}{3}$. - For $21 : 7$, $\frac{21}{7} = 3$, which is not equal to $\frac{7}{3}$. - For $28 : 12$, simplify by dividing numerator and denominator by 4: $\frac{28}{12} = \frac{7}{3}$. - For $49 : 9$, $\frac{49}{9}$ is approximately 5.44, not equal to $\frac{7}{3}$. - For $12 : 8$, simplify by dividing numerator and denominator by 4: $\frac{12}{8} = \frac{3}{2}$, not equal to $\frac{7}{3}$. 4. Therefore, the ratio equivalent to $7 : 3$ is $28 : 12$. Final answer: $28 : 12$