You want to keep the variable on the left and number on right.
So, we need to get rid of 9 and -4y. Let's start with 9.
4y+9=-4y-7
Subtract nine from both sides.
4y=-4y-16
Now add 4y on both sides.
8y=-16
Finally, divide both sides by 8 to get y=-?.
8y/8=-16/8
Therefore, the answer is y=-2.