What steps do you perform to apply a 15% discount to a product in a customer's invoice. Select an answer: In the discount boxes below the invoice table, choose Discount percent and 15. In the discount boxes below the invoice table, choose Discount amount, calculate the dollar amount for the 15% discount and fill it in the second box with the discount as a negative number. Create a service for discounts, add it to the invoice, calculate the dollar amount for the 15% discount and fill it in the Amount cell as a positive number. Create a service for discounts, add it to the invoice, calculate the dollar amount for the 15% discount and fill it in the Amount cell as a negative number