Решите уравнение: 3*(x-2)-5*(x+1)=-8x.

\[\angle B = x{^\circ};\angle A = (x + 30){^\circ};\]

\[\angle C = \left( \frac{x + 30}{2} \right)^{{^\circ}}.\]

\[x + x + 30 + \frac{x}{2} + 15 = 180\]

\[2,5x + 45 = 180\]

\[2,5x = 135\]

\[x = 54{^\circ}\]

\[\angle A = 54 + 30 = 84{^\circ}.\]

\[\angle C = \frac{84}{2} = 42{^\circ}.\]

\[Ответ:\angle B = 54{^\circ};\angle A = 84{^\circ};\]

\[\angle C = 42{^\circ}.\]