The equations are

Since the coefficients of the x-terms, +1 and -1, 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 3.

                       (Cancel common terms)

                            (Divide: )

Now Substitute 6 for y  in either equation to find the value of x.

   (Equation 1)

                (Multiply:  )

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

          (Apply additive inverse property: )

                 (Apply additive identity property: )

                            (Subtract: )

The solution is .

The solution is .