I don't think these things are grounds for closure (though I admit that if I did not close the tab containing such a question I'd be hard pressed to resist editing it). I am happy to ignore people who choose to write in this way but I wouldn't vote to close.

I do tend to extend a bit more tolerance toward posts where I think English may not be a familiar language for the OP though.

The activity of taking an equation with a variable isolated on the LHS, like V = IR and rewriting it so that a different variable is on the left- e.g. R = V/I -has a particular name where I learned mathematics (and in some other parts of the world), but I cannot find what that activity is typically called in the US. Google seems to suggest it is not called what I call it (e.g. because none of the hits on page 1 of search results seem to have US-usage - eg they say 'maths' rather than 'math')

Any suggestions for what that would be called?

I would probably just call it 'algebraic reshuffling', or something descriptive like that, @Glen_b. What do you call it?

@gung Typically called changing the subject of an equation. It's a whole topic in algebra for teenagers here. Also "changing the subject of a formula", though that's somewhat more often used in physics classes I think.

It seems to be the same expression in the UK.

Terms like "rearranging a formula" or your suggested term are similar but less specific; in the V=IR example, the variable V is the subject of the formula (the thing you will find from the other terms on the RHS), and then in the new formula R is the subject. However if I start with 4 variables in an equation like PV=nRT (the variables being P,V, n and T), none of the variables is the subject of the equation, and if I then rearrange that to P/T = nR/V then I stlll don't have a "subject"

It's a very handy term when outlining a suggestion of a way to solve a problem to someone (e.g. substitute (1) into (2), then change the subject of the equation, then find the minimum). We could say something like "rearrange" but ... it's not quite as specific, because that doesn't necessarily tell you to isolate a variable on the left hand side.

The "change the subject" step implies you need to concern yourself with the question "to which variable?"

By extension, inequalities can also have a subject. For example, when computing lower bounds on sample sizes (in order to at least achieve a particular margin of error say) one will change the subject of the inequality to n.