Different kind of obligation

Joint and solidarity obligation

Michelle and Noemi, solidary debtors,bound themselves to pay Oscar and Peter, solidary creditors, their debt in amount of Php. 200000 on Dec 1, 2015, without the need demand. On Dec 1, 2015, Michelle paid Oscar the amount of 100 000. When Oscar and Peter discovered that of The 200 000 debt of Michelle and Noemi, only 100 000 had been paid, peter immediately went to the house of Michelle to demand payment but Michelle told peter that her obligation was already extinguished. Is Michelle correct? Assuming that Michelle is not correct, what is the remedy of Peter.

Quinn, Rae and Sam borrowed Php 600000 from Tom on feb 1, 2016. They executed a promissory note which stated the following " I promise to pay Tom the obligation as follows : quinn will pay 200000 on march 1 2016;Rae will pay 100000 when he gets married and sam will pay 300000 on July 31, 2017. Signed by quinn, sam and rae." On march 1, 2016, tom made a demand for the payment of 200000 from quinn, but she was insolvent. Thus,tom made a demand from sam for 200000, but sam claimed that his obligation was due only july31, 2017 and that he was not liable for the share of quinn. Is sam correct?