How to prove that 0,999... = 1

Hokay, I gona prove you that 0,999(9) is equivalent 1.
That's simple:

let's define x as 0,999(9),

so 10x = 9,999(9)

10x-x = 9,999(9) - 0,999(9)

9x = 9

x = 1

we've defined earlier that x also = 0,999(9)

so x = 1 = 0,999(9)

That's All!