1. X, Y and Z bind themselves to pay W P30,000. Only X received the money per agreement between X, Y and Z. On the due date of the obligation, has W the right to demand the full payment of P30,000 from Z alone?

2. X, Y and Z promised to pay W solidarily P30,000 on or before September 10 without the need of demand. On September 9, X paid the whole amount of P30,000 to W.

a. How much can X collect from Y and Z?

b. May X collect interest from Y and Z?

c. Suppose Z turns out to be insolvent, how much can X collect from Y?