Answer: C - $0; $40,000
Explanation: From the above question, the phrase 3/10, net 60 means Henry is entitled to a 3% discount if payment is make on or before the 10th day while the net 60 means that the invoice is due in 60 days anytime after the 60th day, the invoice becomes overdue.
From the question, the invoice total is $40,000. since payment was made on the 20th day, it means Henry is not entitles to any discount and so has to pay the whole of $40,000 on the invoice.