Ar cle 520 Where one of the debtors assuming joint and several liabili es has performed his obliga on, o set his obliga on, or placed the subject ma er of the obliga on in escrow, the obliga on of the other debtors owed to the creditor is ex nguished to the corresponding extent, and such a debtor has the right to contribu on against the other debtors in accordance with the provisions of the preceding Ar cle. Where the obliga on of one of the debtors assuming joint and several liabili es is discharged by the creditor, the obliga on of the other debtors assuming joint and several liabili es owed to the creditor is ex nguished to the extent of the share that such a debtor assumes. Where the obliga on of one of the debtors assuming joint and several liabili es has merged with the claim of the creditor to be held by the same person, a er deduc ng such share of obliga on, the creditor’s claim against the other debtors assuming joint and several liabili es con nues to exist. Where a creditor delays in accep ng the performance of one of the debtors assuming joint and several liabili es, such delay takes e ect on the other debtors assuming joint and several liabili es. Ar cle 521 Where it is di cult to determine the share among the creditors with joint and several claims, each creditor is deemed to have an equal share. A creditor who has accepted the performance of obliga on in excess of his own share shall reimburse the other creditors with joint and several claims with him on a pro rata basis. The relevant provisions on a joint and several obliga on in this Chapter may be applied to a joint and several claim muta s mutandis. Ar cle 522 Where the par es agree that the debtor shall perform the obliga on to a third person, if the debtor fails to perform the obliga on to the third person or the performance does not conform to the agreement, the debtor shall bear default liability to the creditor. Where it is provided by law or agreed by the par es that a third person may directly request the debtor to perform the obliga on to him, and the third person does not explicitly reject it within a reasonable period of me, if the debtor fails to perform the obliga on to the third person or the performance does not conform to the agreement, the third person may request the debtor to bear default liability. The defenses that the debtor has against the creditor may be asserted against the third person. Ar cle 523 Where the par es agree that the obliga on shall be performed by a third person to the creditor, if the third person fails to perform the obliga on or the performance does not conform to the agreement, the debtor shall bear default liability to the creditor. Ar cle 524 Where a debtor fails to perform an obliga on, and a third person has an lawful interest in the performance of the obliga on, the third person is en tled to perform it to the creditor on behalf of the debtor, unless the obliga on may only be performed by the debtor based on the nature of the obliga on, as agreed by the par es, or as provided by law. A er the creditor accepts the performance of such obliga on by the third person, his claim against the debtor shall be assigned to the third person, unless otherwise agreed by the debtor and the third person. Ar cle 525 Where the par es have mutual obliga ons to each other and there is an order of performance of the obliga ons, the par es shall perform the obliga ons at the same me. Any party has the right to reject the other party's request for performance before the other party performs. Any party has the right to reject the other party's request for the corresponding performance if the other party’s performance does not conform to the agreement. ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti tt ft ti ti ti ti ti ff ti ti ti ti ffi ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ti ff 58 ft ti right to contribu on against the other debtors assuming joint and several liabili es to the extent of the share not performed by the other debtors, and accordingly shall be en tled to the rights of a creditor, provided that the other creditors’ interests shall not be harmed. The defenses of the other debtors assuming joint and several liabili es against the creditor may be asserted against such a debtor. Where a debtor assuming joint and several liabili es against whom the right to contribu on is claimed is unable to perform the share he is liable to assume, the other debtors assuming joint and several liabili es shall be liable for the relevant part of the obliga on on a pro rata basis.