P = A \cdot \frac{1-(1+i)^{-n}}{i} + \frac{B}{(1+i)^n}
A = \left(P - \frac{B}{(1+i)^n}\right)\cdot \frac{i}{1-(1+i)^{-n}}
A = \frac{P - B}{n}
For a loan with principal $P$, periodic rate $i$ (APR converted to per-period), number of periods $n$, and a balloon $B$ due at maturity, the present value identity is: $P = A \cdot \frac{1-(1+i)^{-n}}{i} + \frac{B}{(1+i)^n}$ Solving for the regular payment $A$: $A = \left(P - \frac{B}{(1+i)^n}\right)\cdot \frac{i}{1-(1+i)^{-n}}$ Special case if $i=0$: $A = \frac{P - B}{n}$