There are non-imperative logic programming languages (Prolog) where something like that would work. And those of us who started with imperative coding are probably just as confused by them in the other direction.

That's why I qualified the statement with "conventional". Prolog is not a conventional language, in the sense that most programmers don't know it (and I'd wager close to half of programmers have never even heard of it, if not more). C, C++, Java, JavaScript, PHP, Python, Perl, Ruby, even Rust are all imperative languages at their core and represent the dominant group of languages in conventional use.

If the OP was teaching people a language like Prolog then there wouldn't have been the same confusion.

Verilog and other HDL languages work this way, its not an accident humans would start this way as well as the natural world works in parallel.

I actually started writing a comment about that. Teaching VHDL (my experience) to most programmers is an entertaining experience because they expect effects to be immediate, not executed collectively and simultaneously but mediated by a clock or other mechanism. So in an HDL:

  x <= y;
  y <= y * 20;

These two effects actually occur simultaneously, which is different again from what mathematically inclined learners might expect since there is still mutation. It is more akin to the common notation:

  x' = y
  y' = y * 20

Where the ' indicates the next value of x or y (as opposed to the derivative). Or perhaps:

  x_n = y_{n-1}
  y_n = y_{n-1} * 20

And many programming languages don't even have a good notion for similar parallel evaluation and assignment. Python does, with:

  x, y = y, y * 20

Common Lisp has psetf which permits this:

  (psetf x y
         y (* y 20))

Languages with pattern matching/destructuring bind are your best bet for writing this directly without needing temporary variables.