1. A, B and C are indebted to X in the amount of P3,000. On due date, from whom may X collect the payment?
2. "I promise to pay X the sum of P10,000 Signed by: A and B". Is this joint or solidary obligation?
3. "We promise to pay X P10,000 Signed by A and B". Is this joint or solidary obligation?
4. X, Y and Z are the solidary creditors of A in the sumof P30,000. Y made a demand on A but the latter paid the whole amount to Z. Is the obligation extinguished?
5. A , B and C are individually and collectively indebted to X in the sum of P300,000. Despite several demands, the debtors failed to pay. X sued B only for the whole amount. Is this proper?

The answers should be based on the Law of Contracts and Obligation in the Phillippines.