All of that over, mean of the x's times the mean of the x's is just going to be the mean of the x's squared minus over here you have the mean of the x squared. And that's what we get for m. And then if we want to solve for b, we literally can just substitute back into either equation, but this equation right here is simpler. And so if we wanted to solve for b there, we can solve for b in terms of m. We just subtract m times the mean of x's from both sides. We get b is equal to the mean of the y's minus m times the mean of the x's. So what you do is you take your data points, you find the mean of the x's, the mean of the y's, the mean of the x y's, the mean of the x's squared. You find your m. Once you find your m, then you can substitute back in here and you find your b. And then you have your actual optimal line.