who is correct and why?

Question

Carla and Mandy are solving the inequality below.
–4x ≥ 12

 

Carla says the solution is x ≤ –3, while Mandy says the solution is x ≥ –3. Which student is correct? What mistake
was made by the other student?

Answer 1

-4x ≥ 12

 

Divide both sides by -4, and remember to invert the inequality, because you are dividing by a negative number.

 

x ≤ -3

 

Carla is correct.  Mandy failed to invert the inequality when multiplying or dividing by a negative number.