Krickis 
Literary siren
I'mn the fifth line it simplifies by removing the (a-b) on both sides but since we know that a=b then a-b can only equal 0. Ergo that equation was (a+b)*0=b*0 which is true, but you can't simplify that by removing the zeros because you can't divide by zero. So yeah if you want to ignore a rule of math then surprise you get weird math =p