By what number should we multiply

Let the number be $\mathrm{x}$.

$\therefore \mathrm{x} \times \frac{-8}{13}=24$

or $\mathrm{x}=24 \div \frac{-8}{13}$

or $\mathrm{x}=24 \times \frac{13}{-8}$

or $x=-39$

Thus, the number is $-39$.