The equations are

Rewrite the second equation

 Since the coefficients of the y-terms,+1 and -1,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)

                       (Divide each side by negative 3)

                             (Cancel common terms)

                               (Divide:  )

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

   (Equation 1)

                          (Multiply:  )                           

           (Add 30 to each side)

           (Commutative property:  a+b=b+a)

                        (Additive inverse property: )

                          (Additive indentity property: )

                                  (Add:  )

                     (Multiply each side by negative one)

                              (Product of two same signs is positive)

                                 (Product of two diffirent signs is negative)

The solution is .

The solution is .