Here goes...
Assume that a=b
Therefore, a+a=a+b
Which can be simplified to 2a=a+b
Subtract 2b from both sides, like this: 2a-2b=a+b-2b
Redistribute the left and subtract the right and yield 2(a-b)=a-b
Divide by (a-b), which is zero in this equation, and the result is...
2=1
What now, an earthquake?
Ok so basically you start out with a=b, correct? Well let's assign a value to both variables here:
a=1
b=2
Now the equation is 1=2, the first problem. However if you set them equal to eachother:
a=1
b=1
Then you would get 1=1, a completely legal equation. But next you say a+a=a+b
Now, this with the 2nd pair of variables is completely true, 1+1=1+1. This is kinda strange, but what the hell. Next you simplify apparently to 1(2)=1+1. Then this is the irrational part.
You pull 2b out of your ass and then start flinging it around everywhere.
1(2)-2(1)=(1+1)-2(1)
This equation is now:
0=0
I have no idea what you did for that second to last part, and then the last part is rendered useless. But congrats, you just stated that zero equals zero.