Group by variable and Factor:
Adding a 1 inside the parenthesis really means that you have added 4 to the left side. Also, in the group of y-terms, adding 4 inside, with a minus in the front, means you have subtracted 4 from the left side. So we do the same two things to the right side:
Complete the square, then divide both sides by 16, to get
Does this resemble a form of equation you're familiar with?
The rest should be straight-forward. Good luck!!