Answer
$\dfrac{-2}{7}$
Work Step by Step
RECALL:
$\dfrac{a}{b} \div \dfrac{c}{d} = \dfrac{a}{b} \times \dfrac{d}{c}$
Use the rule above to obtain:
$=\dfrac{8}{y} \times \dfrac{-y}{28}$
Cancel out the common factors, and then multiply to obtain:
$\require{cancel}
\\=\dfrac{\cancel{8}2}{\cancel{y}} \times \dfrac{-\cancel{y}}{\cancel{28}7}
\\=\dfrac{-2}{7}$
