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)

Apply division property of equality: 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:  )

Apply addition property of equality: Add 30 to each side.

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

             (Apply additive inverse property: )

                (Apply additive identity property: )

                         (Add:  )

Apply multiplication property of equality: 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 .