Lol, I corrected my mistake. As for showing examples, if I had a working example, I would have used it already to solve the puzzle!
But here how it works in my mind, we have 2 and 4 as our base known points, and two unknown keys, we pick 15 and 20  for simplicity, we start by subtracting 2 from 15 and 4 from 15.

Now we have two new mutual keys, 11 and 13, if we subtract 11 from 20 we will have 9 which by subtracting 2*4 = 8 from it, we will have half of our first base point "2" ( aka 1).

Second step, we subtract 13 from 20 to have 7, now if we subtract 2+4 = 6 from it, we still have the half of our first base point "2" ( aka 1).

Therefore we have a triangle 2, 4 and 1, our known keys, and then we have 7, 9, 11, 13, 15, 20! Wait that turned into a threesome of triangles, 🤣 anyways the quantity of triangles is insignificant  compared to the quality of our equation.

The important part, if we do 2+4 = 6 *4 = 24, we now have 20 + 4 = 24, because we know 4, by adding it to x= 20(unknown key) we can observe whether any of our results are mutually related or not.

More complicated equation, we do the following, 2*4 = 8*2 = 16, now adding 4 to it, we will observe our x= 20 again.

Trick is picking your base points carefully, otherwise you will be doing things blindly. Find mutual keys that's all.😉