1. X, Y and Z owe A jointly P3,000. Subsequently, A donates to X his credit against the latter. Are Y and Z still liable to A?
2. X owes Y P2,000 payable on July 31, 20020. Y binds himself to deliver to X one sack of rice worth P2,000 on July 31, 2020. Will compensation take place?
3. A owes B P500,000 payable after one year. One week after from date of contract, A and B agree to secure the obligation by a real estate mortgage (sangla ng lupain). Is there a novation? Explain.