Answer:
Derek did it wrong that he did not change the inequality sign while dividing both side terms of the inequality by - 3.
Step-by-step explanation:
We are going to solve an equation of inequality of single variable x.
We will start with, -3x + 5 > 20
⇒ -3x + 5 - 5 > 20 - 5
⇒ - 3x > 15
⇒ [tex]\frac{-3x}{-3} < \frac{15}{-3}[/tex]
⇒ x < - 5
Therefore, while dividing both side terms by -3, the inequality sign will change from > to < sign.
So, Derek did it wrong that he did not change the inequality sign while dividing both side terms of the inequality by a negative number. (Answer)