Exercise 1 Page 415

Recall that ratios form a proportion when the ratios are equivalent. Thus, to determine if the given ratios are equivalent, we will rewrite the ratios in their simplest form. If the resultant ratios are equivalent, then the ratios form a proportion. From here, since $\frac{5}{3}$ is in its simplest form, we will simplify $\frac{35}{21}.$ Because the resultant ratio and $\frac{5}{3}$ are equivalent, $\frac{5}{3}$ and $\frac{35}{21}$ form a proportion.