You could still say something like "rearrange to find an inequality in terms of n" I guess, but it doesn't so clearly/firmly say to "isolate n" in quite the same direct way.

@Glen_b My data suggests that you are a very kind person. See new edit in stats.meta.stackexchange.com/q/4567/99274

@Glen_b, you're right that 'algebraic reshuffling' is much less specific. I don't recall having heard the phrase, 'changing the subject of the equation', but it's also possible that I just missed it.

As far as I can tell it's not used in the US; I presumed there must be a corresponding expression

@Carl You appear to have edited the question but it's unclear what you're asking me to do about it.

@Glen_b Why nothing special. I did propose a new answer within that re-edited question, but, mostly I was just giving you a compliment for beingkind-hearted.

Oh, okay, thanks. I misunderstood.

@Glen_b Hammersley, J. M. 1973. Maxims for manipulators. Bulletin of the Institute of Mathematics and its Applications 9: 276–280 springs to mind as a reference, except that I can't locate a copy on the web or remember much about it. My formal education in mathematics stopped at age 17 but I think I would talk of rearranging or shuffling terms.

@Nick thanks for that. the term "changing the subject" in relation to equations/formulas is apparently used in the UK; when I searched, I mostly got UK sites in the hits.

@Nick Unfortunately my library doesn't seem to hold this (though the new catalog is so bad it's impossible to be more than moderately sure); I shall have to see what I can do to get a copy; it sounds like something I should make sure to be familiar with.

@Glen_b Google "isolate unknown variable".

@whuber thanks