First you have to leave your y alone so you want to move the -1. Since you are moving it to the other side it will now become a +1. It will be +1-9 which will equal to -8. Now you have -8=-2y. You want to permanently leave the y alone so now you divide by 2. (-8/-2=-2y/-2) It should be 4=y. That means that 4 is your answer. Remember to make your answer a positive number because it is a negative divided by a negative!