The inequality is .

Apply subtraction property of inequality: Subtract 12 from each side.

  (Comutative property:)

            (Additive inverse property: )

               (Additive identity property: )

                       (Subtract: )

          (Multiply each side by negative one and flip the symbol)   

                      (product of two same signs is positive) 

Graph the solution set on a number line

Note: A circle means that this point is not included in the solution set.

Check:

To check, substitute a number less than -28, in .

         (Substitute:d=30)

               (product of two same signs is positive)

                       (Add:)

The inequality is true.

The inequality solution set is .