And that's the interesting thing, because you might say, hey, why wouldn't it be the difference? We had the differences over here, so let's experiment with this a little bit. The variance of random variable A is the same thing as the variance of X minus Y, which is equal to the variance of X plus negative Y. These are equivalent statements. So you could view this as being equal to, just using this over here, the sum of these two variances. So it's going to be equal to the sum of the variance of X plus the variance of negative Y. And what I need to show you is that the variance of negative Y, the negative of that random variable, is going to be the same thing as the variance of Y.