Answer: Yes. The younger brother will prevail in his claim since he has performed under a valid contract.
Step-by-step explanation:
Based on the information given, the younger brother will prevail in his claim because he has performed under a valid contract.
Based on the information given, he entered into a valid contract with his elder brother, accepted the offer and complied with its terms from that day forward. Since he performed the contract, he's entitled to the $15000 when after his brother's death.