The equations are

                     Equation (1)

                  Equation (2)

Eliminate the variable n by adding the equation (1) and (2).

        (Add the corresponding columns)

                       (Divide each side by 8)

                      (Cancel common terms)

                           (Divide: )

Substitute in equation (1).

        (Subtract 2 from each side)

        (Apply Commutative property: )

              (Apply Additive inverse property: )

                (Apply Additive identity property: )

                     (Subtract: )

         (Multiply each side by negative one)

                  (Product of two same signs is posivite)

                      (Product of twodifferent signs is negative)

The solution is  

The solution is .