Answer:
You have to subtract 16 from both sides, because you're trying to get y/4 by its self.
Explanation:
After you subtract 16 from 19 you'll get 3. So you'll have y/4 = 3. To get y by its self, you'd have to do the inverse of division, and so you'd multiply 4 on both sides. Your answer would be y = 12.
I'm not sure if you need the second explanation I provided, but it will be there if you need it.