The inequality is .

Apply addition property of inequality: Add 3 to each side.

   (Apply additive inverse property: )

         (Apply additive identity property: )

  (Apply commutative property of addition: a + b = b + a) \ \

                (Add: 6 + 3 = 9)

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

          (Apply additive inverse property: )

                (Apply additive identity property: )

                         (Subtract: )

Graph the solution set on a number line.

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

Check:

To check, substitute a number less than or equal to 9 in .

      (Substitute y = 9)

          (Multiply: )

              (Add: 6 + 9 = 15)

                    (Subtract: ) \ \

The inequality is true.

The inequality solution set is .