 times you want to find an optimum output, an optimum objective for your decision model changing more than one or more than two variables. There's a great tool in Excel called Solver and I just want to give you an introduction to it. We're not going to go into the depths of Solver yet, we'll do that later, but this will give you an idea of the power of Solver. In this case we want to have an objective of maximizing profit down here in B17 and our decision variables are RQ and S, RS the discount price and the purchase quantity and we've got some constraints. R has to be less than 25 cents a copy, Q has got to be greater than 34 but less than 4,000 and S has got to be less than 12 cents for a discount price. We use Solver by going to Data, Solver and you may have to install Solver or activate Solver in order for it to show. Let me show you that real quick. Go to File, Options, Add Ends, down at the bottom, Excel Add Ends, Go and it'll bring up a list of add-ins. Solver should be there but it may not be checked. If it's not checked, check it. You won't necessarily have these other tools. These are things I've added on to mine but look for Solver, check it to make sure it is checked and then click OK and then it will show up under your Data tab. Okay so now we've got Solver installed. I want to click on Solver and bring up a dialog box. We need to set our objective which was Maximize Profit so I'm going to get rid of that and click down here on my profit cell and we want to maximize it. You notice you can minimize or set it to a particular value. We want to change cells, our decision variables are R, Q and S so I'm going to get rid of those and I'm going to click in R, S, Q. Those are my decision variables and then we've got the constraints and I've already got them set up but I'll show you how to do that. I'm going to click on this one about S being less than 12 and delete it and I'm going to add one back and the cell reference here S which is that cell has got to be less than or equal 12 cents so it's already less than or equal. You can see you can select the various forms of equality there. Later on in the course we'll show you how to use these other options there but we want to be less than or equal 0.12. Click OK. Now we've got solvers set up. Just leave everything else the default. We want all the unconstrained variables to be non-negative. Negative values don't make sense. We'll just leave it as the solving method GR linear and click solve and that quickly assuming how your complex your model is we get a solution and it shows that we can get a max profit of 5.20 by raising the selling price to 25 cents which makes sense. This is kind of a very simplistic model and purchasing exactly what the demand is and we're limited by 4,000 so we can't purchase more than that. So that is how quickly solver can find an optimum value. It's a great tool. We'll get into it more depth in the next module.