$A$ straight angle has measure......... (in $^{\circ}$)

For what value of $x+y$ in the figure will $ABC$ be a straight line? Justify your answer.

If two interior angles on the same side of a transversal intersecting two parallel lines are in the ratio $2:3,$ then the greater of the two angles is (in $^{\circ}$)

In $\Delta ABC$,if $\angle A = \angle B = \angle C$,then $\angle B = \dots$ (in $^{\circ}$)

Prove that the sum of angles of any convex quadrilateral is $360^{\circ} .$

If two parallel lines are intersected by a transversal,then each pair of corresponding angles are...........