Let A and B be two C-algebras such that B is prime. In this paper, we investigate the additivity of maps from A onto B that are bijective, unital and that satisfy (AP + PA) = (A)(P) + (P)(A); for all A 2 A and P 2 fP1; IA P1g where P1 is a nontriv- ial projection in A. If is a non-zero complex number such that jj ̸= 1, then is additive. Moreover, if is rational, then is -additive.
