The last inequality is false because -6 is neither equal to -12, nor is -6 smaller than -12. Use a vertical number line to see that -6 is above -12, so it should be -12 ≤ -6.
Since -6 ≤ -12 is false, that makes 3w ≤ -12 false when w = -2.
Therefore, w = -2 is <u>not</u> a solution to the given inequality.