Goods are sold on credit by the supplier to one of its customers, amounting to $20,000. The credit was granted as per the term of sale with 3/15 net 40. Now, according to terms, a $20,000 trade credit is given to the customer for 40 days from the date of the invoice issued. However, as per the term of sale, if the payment is made by the customer to the supplier within 15 days from the date when the invoice was issued to the customer, then the cash discount of 3% will be given to the customer. Customer is required to make payment of: