A, B, C and D are obliged to give X, Y and Z P24,000.

a. To what extent may Z validly demand from B?Until B have done his obligation

b. If there is active solidarity, to what extent may Z validly demand from B?A solidary obligation is almost always an advantage for a creditor because it will either allow any Z or creditor can validly demand B or debtor, the entirety of the debt from the sole debtor when the solidarity is active.

c. If there is passive solidarity, to what extent may Z validly demand from B?It will allow the Z or creditor to demand the entirety of the debt from any of the multiple B or debtors when it is passive.

d. If there is mixed solidarity, to what extent may Z validly demand from B?Mixed Solidarit is on the part of both the creditor and debtor. Z can validly demand B until the entire compliance with the obligation.

A, B, C and D, solidary debtors, are obliged to give X, Y and Z, solidary creditors, P24,000.

a. X renounces the whole obligation without the consent

of Y and Z. The debtors accepted the renunciation. What is the legal effect of the renunciation? What is the extent of X's liability, if any?Renunciation is a rule of law that any one may renounce a right which the law has established in his favor. The legal effect of it X can make a decision that will benefit more for him/her or only for him/her because he/she has a power of making a will.

b. X renounces the share of A who accepted the renunciation. Thereafter B becomes insolvent. What is the extent of A, C and D's respective liabilities, if any? They are joint liability and therefore the debts are distinct from one another. If it is Solidary Obligation each of the debtors/creditors is bound to render/demand. A, C and D's respective liabilities is 2000.

c. X renounces P2,000 from the share of A who accepted the renunciation. Thereafter B and C becomes insolvent. What is the extent of A and D's respective liabilities, if any? Each of the creditors can only collect 4000 from A and D because B and C becomes insolvent.

d. X renounces the share of A after B paid the entire debt. What is the legal effect of the renunciation?

I guess B, C and D take advantage to A; they don’t need to pay for their part in debt because A paid for entire debt.