The equations are

                                         Equaton(1)

                                           Equaton(2)

Substitute for y in the Equation (2).

Apply subtraction property of equality; if a = b, then .

    (Subtract x from each side)

                  (Apply additive inverse property:  )

                       (Subtract: )

Apply addition property of equality; if a = b, then a + c = b + c.

           (Add 4 to each side)

                   (Apply additive inverse property:  )

                              (Add: 4 + 4 = 8)

Apply division property of equality: if a = b, then.

                         (Divide each side by 2)

                              (Cancel common terms)

                                 (Divide: )

Substitute 4 for x in equation (2).

                                (Add: )

The solution is (4, 8).