What is the a possible equation for 212?

Answer 1

I assume you want an equation with a solution of 212. Just write:

x = 212

If you want something more fancy, do something to both sides of the equation - this is basically the opposite of what you do to solve an equation. For example, you can multiply both sides of the equation by some number (the same on both sides, of course), add the same number to both sides, square both sides (note that this will most likely add additional solutions, that are not solutions to the original equation), etc. If you already know a bit about more advanced math, you can take logs or antilogs on both sides, take sines or inverse sines on both sides, etc. (this, too, may introduce additional solutions).