What you want to do is isolate the y variable. So to do this you must get rid of the three that is being multiplied by y. The opposite of multiplication is division. Whatever you do on one side you do to the other so divide 3y by 3 and then divide -8 by 3. This cancels out the 3 and you should get y=-8/3 or y=-2 & 2/3 depending on if your teacher wants mixed fractions or not :)