21. Determine the amount to be paid in full settlement of each invoice, assuming that credit for returns and allowances was received prior to payment and that all invoices were paid within the discount period. Merchandise $4,500 Freight Paid by Seller $140 Returns and Allowances $1,200 (a) Freight Terms FOB Shipping Point, 2/10, net 30 FOB Destination, 1/10, net 45 $7,650 $200 $450 (b)