Chapter 2 - Equations, Inequalities, and Problem Solving - 2.1 Solving Equations - 2.1 Exercise Set - Page 87: 76

$x=-\dfrac{4}{3}$

Using properties of equality, the solution to the given equation, $ -15x=20 $, is \begin{array}{l}\require{cancel} \dfrac{-15x}{-15}=\dfrac{20}{-15} \\\\ x=\dfrac{20}{-15} \\\\ x=-\dfrac{\cancel{5}\cdot4}{\cancel{5}\cdot3} \\\\ x=-\dfrac{4}{3} .\end{array}