The inequality is .

Case 1: If a  b Then

Case 2: If a b Then

Multiply each side by negative one and flip the symbol.

                  (Product of two same signs is positive)

Solve inequality for case 1.

Apply subtraction property of inequality: Subtract 4 from each side.

               (Apply additive inverse property: )

                     (Subtract: )

Solve inequality for case 2.

Apply subtraction property of equality: Subtract 4 from each side.

                   (Apply additive inverse property: )

                     (Subtract: )

Graph the solution set on a number line.

Note: A dot means that this point is included in the solution set.

The solution set is .