Totals: set this lbrs BackColor property Calculate Exit Figure 3-37 User interface for Exercise 11 12. In this exercise, you modify the Chopkins Toys application from Exercise 11. Use Windows to make a copy of the Chopkins Solution folder. Rename the copy Modified Chopkins Solution. Open the Chopkins Solution.sin file contained in the Modified Chopkins Solution folder. Modify the interface as shown in Figure 3-38. The interface will now display the sale totals for each of the different packs. For example, if the customer purchased five 12 packs, the label that appears next to the associated text box should display 74.95 (5 14.99). Modify the btnCalc_Click procedure appropriately. The procedure should also allow the user to enter the shipping charge, which should be added to the total sale amount. Save the solution and then start and test the application Chopkins Toys 12 pack: 5 pack 2 pack: Shipping: Totals: Calculate Exit Figure 3-38 User interface for Exercise 12