Solution:
This step:
Divide by (A-B):
If A = B, then A - B = 0.
So we can rewrite as:
Divide by 0
Which obviously doesn't work. :>
Here's another one.
Imagine the number 0.99999999999999.... with 9's recurring into infinity.
I propose that 0.999... = 1
Sounds counterintuitive?
Think about it this way.
Imagine a "one-third" represented as a fraction:

If we multiply one-third by 3, we get 1. Right?

* 3 = 1
Right...?
So how do we represent

in decimals?
It's 0.3333333333333... recurring.
If we multiply by 3, we get:
0.99999999999.... recurring.
Therefore, 0.999999999.. recurring to infinity, is equal to 1.
They are the same number.