[tex]\it \hat A+\hat B+\hat C=360^o\ \ \ \ \ (1)\\ \\ \hat A=\hat C+24^o\ \ \ \ \ (2)\\ \\ \hat B=\hat C-9^o\ \ \ \ \ \ (3) \\ \\ (1),\ (2),\ (3) \Rightarrow \hat C+24^o+\hat C-9^o+\hat C=360^o \Rightarrow 3\hat C+15^o=360^o|_{-15^o }\Rightarrow\\ \\ \Rightarrow 3\hat C=115^o \ \ \ \ \ (4)\\ \\ (2),\ (4) \Rightarrow \hat A=115^o+24^o=139^o\\ \\ (3),\ (4) \Rightarrow \hat B=115^o-9^o=106^o[/tex]