[tex]Sum\ of\ angles\ in\ triangle\ is\ equal\ to\ 180^{\circ}\\\\
To\ find\ x\ sum\ all\ angles:\\
2x+x-45+x-15=180\\\\
4x-60=180\ \ \ |Add\ 60\\\\
4x=60+180\\\\
4x=240\ \ \ |Divided\ by\ 4\\\\
x=60^{\circ}\\\\
\angle \ A=2x=2*60=120^{\circ}\\
\angle\ B=x-45=60-45=15^{\circ}\\
\angle\ C=x-15=60-15=45^{\circ}\\\\Triangle\ is\ \textbf{obtuse}.[/tex]