Joint Obligations to Obligations with a Penal Clause

Karen and Kelsey made themselves solidarity indebted to Lara for the amount of P50,000.00. When Lara demanded payment from Karen, the latter refused to pay Kelseys share of P25,000. According to Karen, Kelsey was declared legally insolvent, hence Kelseys obligation to Lara is extinguished. How much can Lara collect from Kelsey? Explain your answer.