If two lines intersect each other,then the vertically opposite angles are.........

$\angle ABD$ and $\angle ACE$ are exterior angles of $\Delta ABC$. If $\angle ABD = 140^{\circ}$ and $\angle ACE = 80^{\circ}$,then find $\angle A$. (in $^{\circ}$)

In the figure,if $AB \parallel CD$,$\angle BMX = 125^{\circ}$ and $\angle CNX = 55^{\circ}$,find $\angle MXN$. (in $^{\circ}$)

If in the figure,bisectors $AP$ and $BQ$ of the alternate interior angles are parallel,then show that $l \parallel m$.

$\angle ABC$ and $\angle ABD$ are a linear pair of angles. If $\angle ABC : \angle ABD = 17 : 13$,then find $\angle ABC$ and $\angle ABD$.

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