The equations are

                   Equation (1)

                  Equation (2)

Multiply the equation (2) by 2.

                Equation (3)

Add equation (3) and Equation (1).

                            (Divide each side by 37)

Substitute -3 for p in equation (1).

                          (Multiply:)

Addition property of equality: If a = b then a + c = b + c

             (Add 9 to each side)

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

                             (Apply Additive inverse property: -9 + 9 = 0)

                                        (Add: - 3 + 9 = 6)

Division property of equality: If a = b then a / c = b / c, c ≠ 0.

                                  (Divide each side by 6)

                                       (Cancel common terms)

                                          (Divide:)

The solution is.