This is the expected value of Y times the expected value of X, just written in a different order. And this is the expected value of Y times the expected value of X. We're subtracting it twice and then we're adding it. Or, one way to think about it is that this guy and that guy will cancel out. You could have also picked that guy and that guy. But what do we have left? We have the covariance of these two random variables, X and Y, are equal to the expected value of, I'll switch back to my colors just because this is the final result, the expected value of X times the expected value of the product of XY, the expected value of the product, the expected value of the product, minus, what is this?