The measures of two vertically opposite angles are $(5x + 30^{\circ})$ and $(8x - 60^{\circ})$,then the value of $x = \dots$

Find the measure of an angle,which is one-eighth of the measure of its supplementary angle. (in $^o$)

$\angle ACD$ is an exterior angle of $\Delta ABC$ and the bisector of $\angle A$ intersects $BC$ at $E$. Prove that $\angle ABC + \angle ACD = 2 \angle AEC$.

If one of the two angles of a linear pair has measure $75^{\circ}$,the measure of the other is $\ldots \ldots \ldots$ (in $^{\circ}$)

$\angle A$ and $\angle B$ are complementary angles. If $\angle A = \angle B - 20^{\circ}$,then find $\angle A$ and $\angle B$.

$\angle A$ and $\angle B$ are supplementary angles. If $\angle A = 3x - 10^{\circ}$ and $\angle B = 2x + 30^{\circ}$,then find $\angle A$ and $\angle B$.