Add 12 to all three sides:





Divide all three sides by -4, and since we are
dividing by a negative number, the inequalities
reverse their direction:



It is most common to leave final inequalities in terms of
≤ and < rather that ≥ and >



Since we want interval notation, we plot it on a number line

-----o=======●---------------------
-6  -4  -3  -2  -1   -0   1   2   3  

The interval notation is an abbreviation for the graph on a number line:

    (-4,-2]

Edwin