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)

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

                             (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.