Math Question

I tend to think this has to be a math question first. I see a few different ways to define "% increase". The end result will depend on how you define percent increase.

First thought. Is it supposed to be 105=89+x*89 (where x is the % increase)? The algebra to solve that should be relatively straightforward. This is the most common way I see % increase defined.
Sometimes I see something like 105=89+x*105 (where x is still % increase). Again the algebra should be simple, but the value and meaning of x is slightly different this way.

Those are the two definitions that come immediately to mind, there may be others. In either of those cases, the algebra is simple, and the subsequent programming should also be straightforward.

Hi allgeef,

Looks like
=(B1-A1)/A1

See the attached for my reasoning and answer.
Percent Increase backwards.xlsx