Chapter 1 - Expressions, Equations, and Inequalities - 1-5 Solving Inequalities - Practice and Problem-Solving Exercises - Page 40: 78

$-20$

Distribute the $-3.1$, making the equation $0.4x+1.18=-6.2+0.031x$ Add $6.2$ to both sides, leaving you with $0.4x+7.38=0.031x$ Subtract $0.4x$ from both sides to get $7.38=-0.369x$ Divide both sides by $-0.369$ to get $\frac{7.38}{-0.369}=\frac{-0.369x}{-0.369} \\-20=x$