QUESTION: 1. Elaborate the concept of law on Sales 2. Distinguish dacion en pago, sales, and payment by cession. 3. What is the difference between contract for a piece of work and barter? provide an example. 4. Elaborate the rules on Pricing a product. 5. Distinguish the bilateral promise against unilateral promise. Provide an example. 6. Elaborate the obligations of the vendor. 7. Elaborate each kind of delivery.