## Thinking Mathematically (6th Edition)

$\dfrac{1}{5}$
Convert the mixed number to an improper fraction: $=\dfrac{-3}{7} \div \dfrac{-(7 \cdot 2 + 1)}{7} \\=\dfrac{-3}{7} \div \dfrac{-15}{7}$ Use the rule $\frac{a}{b} \div \frac{c}{d} = \frac{a}{b} \times \frac{d}{c}$: $=\dfrac{-3}{7} \times \dfrac{7}{-15}$ Cancel common factors and then multiply: $\require{cancel} =\dfrac{\cancel{-3}1}{\cancel{7}} \times \dfrac{\cancel{7}}{\cancel{-15}5} \\=\dfrac{1}{5}$