In this paper, we give explicit formulas of the solutions of the two general systems of difference equationswhere n ∈ N 0 , f , g : D −→ R are "1 − 1" continuous functions on D ⊆ R, the initial values x −i , y −i , i = 0, 1, 2, 3 are arbitrary real numbers in D and the parameters a, b, c and d are arbitrary real numbers. Our results considerably extend some existing results in the literature.