This right over here is the derivative of x minus y squared with respect to x minus y. And then this right over here is the derivative of x minus y with respect to x. Just the chain rule. Now let's go to the right-hand side of this equation. This is going to be equal to the derivative of x with respect to x is 1. The derivative of y with respect to x, we're just going to write that as the derivative of y with respect to x. And then finally, the derivative with respect to x of a constant, that's just going to be equal to 0.