Read the problem. What number do you always end up with and why?

Question

Pick any number and double it. Add 56 to this result. Divide the sum by 2. Subtract the original number you picked.

Answer 1

If you start off with x:
Double it: 2x
Add 56 to this result: 2x + 56
Divide the sum by 2: (2x + 56) / 2 = x + 28
Subtract the original number you picked:
(x+28) - x = 28.

Answer 2

The reason it ends up the same number is because of the last line "subtract the original number you picked."

Basic principles of algebra allow you to add/subtract in any order you want (associative property), so that is why even though you are waiting until the end to subtract your original number it has the same result)