Question 365600
P = A/1+rt
 
if rt != -1, P + Prt = A, by multiplying
 
 Prt = A - P, by substracting P
 
 if Pt != 0, then r = (A-P)/Pt
 
 if Pt = 0, then, if P = 0, t != 0, then solution exist if A = 0 forall r
 
 if P != 0, t = 0, solution if A = P forall r
 
 if P = 0, t = 0, solution if A = 0 forall r

if rt = -1, no solution exit