The equations are .

                  Equation (1)

          Equation (2)

Since the coefficient of a is same in both equations, either equation can be used for solution. Solve the first equation for a.

Apply subtraction property of equality: If a = b then a b = b a.

               (Subtract b from each side)

                           (Apply additive inverse property: )

Substitute in equation (2).

Distribute terms using distributive property: a(b c)= ab ac.

                       (Add: )

Apply addition property of equality: If a = b then a + b = b + a.

         (Add 2b to each side) \ \

                          (Apply additive identity property: ) \ \

Apply addition property of equality: If a = b then a + b = b + a.

              (Add 1 to each side)

Apply commutative property of addition: .

                             (Apply additive inverse property: )

                                   (Add: 5 + 1 = 6) \ \

Apply division property of equality: If a = b then .

                              (Divide each side by 2)

                                   (Cancel common terms) \ \

                                     (Divide: )

Substitute in equation .

                                  (Add: 8 + 1 = 9)

The solution is .