 Okay, since quite a few of you are having problems with building the model and with constructing the data table, I want to show you how it is done or how I did it. The model really isn't that complicated. Just basic business economics. We've got a price, the number of sales. Revenue is just price times sales. The cost is just equal to the unit sole times the unit cost of each item. Profit is the difference between revenue and cost and then you total those up to get the total profit for the model. I guess the complicated part is to remember that you run that regression, actually two regressions to determine the relationship between the prices of A and B and the sales of A and B. And in the model you put that regression formula to determine the sales. You can see here how it's linked back. The number of sales of A is dependent upon the price of B and the price of A. And it's a inverse relationship for the price. As the price of A goes up, sales of A's go down. But on the other hand, as the price of B goes up, sales of A increase. So you have that equation in this cell here. And then to do the data table, you remember that I said we wanted to vary the price of A from 200 to 600 at $50 increments and the price of B the same from 200 to $650 increments. And when you start setting your table up, you've got to have an objective cell. In that case, it's the total profit. And you can see how it's linked back to the model. Total profit here is linked back to the total profit there, which in turn is linked all the way back to these prices of A and B. So let's just go ahead and set up the data table. Once we've got this basic structure, this Excel is acting up, as I said in one of my messages. I had to remove those precedent errors. And we're going to select this area where we want the data table to be, go to data, what if data table input cell is going to be price of model A, column input cell is price of model B. And then we just click OK. And we get our values. And I'm going to expand those just a little bit so you can see, get rid of those pound signs. Okay. Here we've got the data table. And you can see it ranges again from, I guess, a loss of $20,000 over here if we set the price of A to be $600 and the price of B to be $200. Go down here to the other extreme. If we set A to be $200 and B to be $600, it's a loss of $22,000 almost. And then if we look around for our maximum, I'm just eyeballing here, it appears that the maximum is about $53,000, which would be a cost of A of around $450 and a cost of B of around $450. So that's really how you do the data table.