If A=PertA = P e^{rt}A=Pert, solve for ttt in terms of A,P,rA, P, rA,P,r.
t=\ac\n(A/P)rt = \ac{\n(A/P)}{r}t=\ac\n(A/P)r
t=\ac\n(A−P)rt = \ac{\n(A-P)}{r}t=\ac\n(A−P)r
t= (A/Pr)t = \ (A/Pr)t= (A/Pr)
t=r (A/P)t = r \ (A/P)t=r (A/P)