Question

Marcie solved the following inequality, and her work is shown below:

−2(x − 5) − 12 ≤ 4 + 6(x + 3)
−2x + 10 − 12 ≤ 4 + 6x + 18
−2x − 2 ≤ 6x + 22
−8x ≤ 24
x ≤ −3

What mistake did Marcie make in solving the inequality

Answer 1

Marcie just left out the 4 on the third line without doing anything to it

Answer 2

The mistake that Marcie made when solving this inequality was forgetting to switch the inequality sign. When solving an inequality, you sometimes divide by a negative to isolate / solve for the variable. When doing so, the inequality sign flips to its opposite.