Modify VB Auto Center project from chapter 5 to separate the business logic from the interface. Create a class for purchases, with properties for each of the options. The class method will calculate the subtotal, tax, total and amount due. Make the About box display on a separate form, rather than a message box.
Add summary totals for the number of sales, total sales and the total trade-ins. maintain the totals as shared read-only properties of the class and display the summary information on a separate form.
This will use the VB Auto Center case study that was completed a month ago.