The equations are

Rewrite the second equation

Apply addition property of equality: Add 9 to each side.

                (Apply additive inverse property: )

   (Add y to each side)

Apply commutative property of addition: a + b = b + a.

                   (Apply additive inverse property: )

                   (Simplify) \ \

 Since the coefficients of the x-terms, +1 and +1, are additive inverses,

you can eliminate these terms by adding the equations. .

Subtract the equations to eliminate variable y.

   (Write the equations in column form and Subtract)

Apply division property of equality: Divide each side by negative 8.

                         (Cancel common terms)

                                  (Divide: )

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

    (Equation 1)

            (Multiply: )

Apply addition property of equality: Add 20 to each side.

Apply commutative property of addition: a + b = b + a.

           (Apply additive inverse property: )

                      (Add: )

The solution is .

The solution is .