.
"Pick any number. Add three to your number. Double your result. Add four to that number.
Divide the result by 2. Finally subtract your original number. Your result is 5."
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
"Pick any number. x
Add three to your number. x + 3
Double your result. 2x + 6
Add four to that number. 2x + 10
Divide the result by 2. x + 5
Finally subtract your original number. Your result is 5." (x + 5) - x = 5.
The age of this joking problem is three thousand years (at least).
------------------------------
Comment from student: How does this work with any starting number?
------------------------------
My response: My written text shows you that it works with any given number "x".