Answer :
[tex]The\ sum\ of\ an\ angles\ of\ a\ triangle\ equal\ 180^o.\\\\\alpha+\beta+\delta=180^o\\\\\alpha+\beta=115^o\\\\therefore\\\\115^o+\delta=180^o\ \ \ \ |subtract\ 115^o\ from\ both\ sides\\\\\delta=65^o\\\\Answer:\huge\boxed{65^o}[/tex]