The product of two rational numbers is -5. If one of these numbers is $\dfrac{-7}{15}$, find the other.

Let the number be $x$.

$\dfrac{-7}{15} \times x = -5\\[1em] \Rightarrow x = -5 ÷ \dfrac{-7}{15}\\[1em] \Rightarrow x = -\dfrac{5}{1} \times \dfrac{-15}{7}\\[1em] \Rightarrow x = \dfrac{5 \times 15}{1 \times 7}\\[1em] \Rightarrow x = \dfrac{75}{7}\\[1em] \Rightarrow x = 10\dfrac{5}{7}$

The other number is $10\dfrac{5}{7}$.