Chapter 3 - Solving Inequalities - 3-3 Solving Inequalities Using Multiplication or Division - Practice and Problem-Solving Exercises - Page 182: 37

Multiply by -4

The second inequality is the first inequality with the variable isolated. In order to cancel out division, we use multiplication, so the inequality can be multiplied by -4 on both sides to get the second inequality. However, because we multiply by a negative, we must flip the inequality sign.