Answer: (x-9)/2 = y
Basically, we ned to get y by itself. I started by multiplying both sides of the equation by y, which will cancel it out from the left side. That gives me x-9 = 2y.
Now, we're going to divide both sides by 2.
That gives me (x-9)/2 = y, which is your answer! I'll attach a photo of the work I did, I hope it makes sense! :)