F = P ( 1 + i ) ^ n
A = F(i) / ((1 + i)^n)-1)
P = F /( (1 + i ) ^ n )
F = ( A (( 1 + i) ^ n) - 1)/ i
i = ( (F/P)^ (1/ n) ) - 1
A = ( P(1+i)^n)( i ) ) / ( (1+i)^n )-1)
