Elimination Method:

The equations are

                        Equation (1)

                                Equation (2)

Multiply the second equation by 3.

                          Equation (3)    

Since the coefficients of the y-terms are additive inverses, you can eliminate

these terms by adding the equations.  Add the equations to eliminate variable y.

Write the equations in column form and add the corresponding columns.

Apply division property of equality: if a = b then 

                              (Divide each side by negative 2)

                                   (Cancel common terms)

                                        (Divide: )

Now, find the y value by substituting in either equation.

                (Equation 1)

                       (Add 9 to each side)

                       (Apply commutative property of addition: )

                                (Apply additive inverse property: )

                                   (Apply additive identity property: )

                                       (Add: )

                             (Multiply each side by negative one)

                                      (Product of two same signs is positive)

The solution is .