Based on the provided information, the invoice date is November 28th, and the terms are 1/8 - 20x.
The term "1/8" represents the discount percentage, and "20x" represents the number of days within which payment should be made to receive the discount.
To calculate the discount date, you need to determine 1/8th of the number of days specified by the term "20x" and then add that to the invoice date.
1/8th of 20 days is 2.5 days, so you would typically round it up to 3 days. Adding 3 days to the invoice date of November 28th, the discount date would be December 1st.
As for the net payment date, it would be the date by which the full payment is due without taking the discount. To find this date, you would add the full 20 days from the invoice date of November 28th. Therefore, the net payment date would be December 18th.