And so what we need to do is express X in terms of Y. So here we just have to solve for X. So one way to do this is, let's see, we can square both sides of, well actually let's divide both sides by four. So you get Y over four is equal to the square root of nine minus X. Now we can square both sides. Y squared over 16 is equal to nine minus X. And then let's see, we could multiply both sides by negative one.