Решите уравнение: 3x+5=2x-1.

\[x{^\circ} - \angle B;2x{^\circ} - \angle A;6x{^\circ} - \angle C.\]

\[x + 2x + 6x = 180\]

\[9x = 180\ \ \ \]

\[x = 20{^\circ}\ \ \ \ \]

\[2 \bullet 20 = 40{^\circ}\ \ \ \ \]

\[6 \bullet 20 = 120{^\circ}\]

\[Ответ:\angle A = 40{^\circ};\ \angle B = 20{^\circ};\ \]

\[\angle C = 120{^\circ}.\]