Cho hai góc kề nhau aOb và aOc. Cho góc aOb = 35°và góc aOc = 55°

$$\begin{gathered} \mathrm{Cho} \mathrm{hai} \mathrm{góc} \mathrm{kề} \mathrm{nhau} \overbrace{\mathrm{aOb}} \mathrm{và} \overbrace{\mathrm{aOc}} \mathrm{sao} \mathrm{cho} \mathrm{góc} \mathrm{aOb} = 35° \mathrm{và} \mathrm{góc} \mathrm{aOc} = 55°. \mathrm{Gọi} \mathrm{Om} \mathrm{là} \mathrm{tia} \mathrm{đối} \mathrm{của} \mathrm{tia} \mathrm{Oc} \\ \mathrm{a}) \mathrm{Tính} \mathrm{số} \mathrm{đo} \mathrm{các} \mathrm{góc}: \overbrace{\mathrm{aOm}} \mathrm{và} \overbrace{\mathrm{bOm}} \\ \mathrm{b}) \mathrm{Gọi} \mathrm{On} \mathrm{là} \mathrm{tia} \mathrm{phân} \mathrm{giác} \mathrm{của} \mathrm{góc} \mathrm{bOm}. \mathrm{Tính} \mathrm{số} \mathrm{đo} \mathrm{góc} \mathrm{aOn}? \\ \mathrm{c}) \mathrm{Vẽ} \mathrm{tia} \mathrm{đối} \mathrm{của} \mathrm{tia} \mathrm{On} \mathrm{là} \mathrm{tia} \mathrm{On}\text{'}. \mathrm{Tính} \mathrm{số} \mathrm{đo} \mathrm{góc} \mathrm{mOn}. \end{gathered}$$