Question:
Divide the sum of $\frac{-13}{5}$ and $\frac{12}{7}$ by the product of $\frac{-31}{7}$ and $\frac{-1}{2}$.
Solution:
$\left(\frac{-13}{5}+\frac{12}{7}\right) \div\left(\frac{-31}{7} \times \frac{-1}{2}\right)$
$=\frac{-13 \times 7+12 \times 5}{35} \div \frac{31}{14}$
$=\frac{-91+60}{35} \div \frac{31}{14}$
$=\frac{-31}{35} \times \frac{14}{31}$
$=\frac{-2}{5}$