i need to do this but am struggeling with the constraint part:

After you have entered this data, enter the label Barrels in cell B8 and enter the sample production run of 5, 10, 5 and 10 in cells C8:F8. Define the name Barrels for these cells.

Name the cells C2:F2 as Profit and enter the label Profit in cell B2 to help remember that these cells give the profit for each barrel made of the respective product.

In cell H8, enter the command =SUMPRODUCT(Barrels,Profit) and enter the label Total Profit in cell H7.

The SUMPRODUCT function can be used to determine the amount of malt, hops and yeast used by a production run. Name the cells C4:F4 as Malt. Name the cells C5:F5 as Hops. Name the cells C6:F6 as Yeast. In cells G4:G6, use the SUMPRODUCT function to calculate the amount of malt, hops and yeast used by the sample production run. You should get 45, 40 and 60 in these cells.

On the Data tab, click on Solver to get the Solver Parameters box. Set the target cell to H8, the Total Profit cell. To maximize total profit, click on the Max button. Enter Barrels for By Changing Cells. This allows Solver to maximize total profit by changing the entries in the barrels cells.

The entrepreneur cannot use more resources than are available. In the Subject to Constraints box, constraints need to be added. Click on the Add button and use the above cell names to add a constraint that ensures that the amount of resources used is less than or equal to the amount of resources that are available. I need help with this part here

Another constraint needs to be added, namely that the entries in the cells named barrels must be greater than or equal to zero. Add this constraint.

Finally, click on the Solve button. What are the number of barrels of Light, Dark, Ale and Premium that should be made to maximize total profit for the month?