Divide:

0 by $\dfrac{7}{-9}$

$0 ÷ \dfrac{7}{-9}\\[1em] = 0 \times \dfrac{-9}{7}\\[1em] = \dfrac{0 \times -9}{1 \times 7}\\[1em] = \dfrac{0}{7}\\[1em] = 0$

Hence, $0 ÷ \dfrac{7}{-9} = 0$