I'm really curious about the solution to Exercise 3. The instructions state "Also calculate the subtotal for each line item (discount is per unit and shipping is a flat cost)."
I interpret a "per unit" discount to be a $ discount ($1 price / unit - $0.06 discount / unit), so I calculated line subtotal as "(([Unit_Price]-[Discount])*[Quantity])+[Shipping_Cost]" but I see in the solution it is supposed to be "((1-[Discount])*[Quantity]*[Unit_Price])+[Shipping_Cost]", which appears to have interpreted that as a % discount.