The equations are

Since the coefficients of the x-terms, -9 and +9, are additive inverses,

you can eliminate these terms by adding the equations. .

add the equations to eliminate variable x.

        (Write the equations in column form and add)

Apply division property of equality: Divide each side by negative 2.

                                (Cancel common terms)

                                     (Divide: )

Now Substitute 7 for y  in either equation to find the value of x.

   (Equation 1)

                (Multiply:  )

Apply subtraction property of equality: Subtract 28 from each side.

          (Apply additive inverse property: )

                 (Apply additive identity property: )

                         (Subtract:  )

Apply division property of equality: Divide each side by negative 9.

                                 (Cancel common terms)

                                      (Divide: )

The solution is .

The solution is .