The difference between the supplementary angle and the complementary angle of any acute angle is............. (in $^{\circ}$)

$A$ transversal intersects two lines in such a way that the two interior angles on the same side of the transversal are equal. Will the two lines always be parallel? Give reason for your answer.

Lines $AB$ and $CD$ intersect at $P$. If $\angle APC = 2x + 30^{\circ}$ and $\angle BPD = 4x - 20^{\circ}$,then find $x$,$\angle APC$,and $\angle BPD$.

Two lines are respectively perpendicular to two parallel lines. Show that they are parallel to each other.

$\angle A$ and $\angle B$ are supplementary angles. If $\angle A : \angle B = 3 : 7$,then $\angle B = \dots$ (in $^o$)

In $\Delta PQR$,$\angle P : \angle Q : \angle R = 5 : 2 : 2$. Find the measure of each angle of $\Delta PQR$.