17BII, 27S: doing TVM calculations inside solver equations

[Dave Britten]

For whatever reason, the 17BII and 27S don't seem to have solver functions for calculating TVM variables, while the 19BII has N(), I%YR(), PV(), PMT(), and FV().

Is there any good way to mimic those functions inside a solver equation on the models that don't have them? I have a formula where I need to be able to calculate both N (where FV=0; PV, PMT, and I% are nonzero), and subsequently FV (using a new value for N) as part of the intermediate results. Do I just need to rearrange the TVM formula given in the manual's appendix?