on approximation of some mixed functional equations

In this paper,  we have improved some of the results in [c. choi and   b. lee, stability of mixed additive-quadratic and additive-drygas functional equations. results math.  75  no. 1 (2020), paper no. 38]. indeed, we investigate the hyers-ulam stability problem of the following functional equations / 2φ(x + y) + φ(x - y) = 3φ(x)+ 3φ(y)    2ψ(x + y) + ψ(x - y) = 3ψ(x) + 2ψ(y) + ψ(-y). we also consider the pexider type functional equation / 2ψ(x + y) + ψ(x - y) = f(x) + g(y), and the additive functional equation 2ψ(x + y) + ψ(x - y) = 3ψ(x) + ψ(y).