Explanation:
Factor the numerator and denominator to get
2 (2x-1)(x-3) / (x-4)(x-3)
so x cannot equal 4 or 3 ( that would make denominator = 0....not allowed)
the (x-3) in the numerator cancels the (x-3) in the denominator to get
2(2x-1) / (x-4) x not equal to 4 or 3