Xue Sheng
All weight is underside
That is a good analogy. I like that. And but the worrying notion for me is knowing what to do when faced with the solvable equation X+5=9 on the one page and seeing on the answers page, the solution advising: X=3 if we know what is good for us.
Interesting point and sadly all to true, I was once involved in a statistical analysis of racial distribution in a certain state office, not because it was my job but because the guy doing it did not know thing one about statistics and he discovered I did. After a whole lot of questions I realized what he was attempting to do which petty much came down to saying in the problem of what is X n X+5=9 that x=15. I told him I would have no part of it and walked away.