And it seems like we have pretty much everything we need to solve for this. So what's the relationship between x, y, and s? Well, we know that this is a right triangle. The streets are perpendicular to each other. So we can use the Pythagorean theorem. We know that x squared plus y squared is going to be equal to s squared. And then we can take the derivative of both sides of this with respect to time to get a relationship between all the things that we care about.