If this factors nicely, you can cancel part of the numerator with the denominator. The whole denominator must go in this question. So let's see if 3y + 1 is a factor of the numerator.
Try factoring the numerator. One factor must be 3y + 1 if this is going to be able to be simplified.
(3y + 1)( y - 6) what should go before the y to get to 12? It should be 4
(3y + 1)(4y - 6) This does not give the correct middle term, so this is not reducable. Do you mean division? If you do, then the answer is 4y with a remainder of - 6/(3y + 1)