Co-interior angles for parallel lines are supplementary. 

When one pair of alternate angles are equal to $45°$ then the second pair of alternate angles will be equal to _____$°$.

If one co-interior angle is $42°$ then the other co-interior angles will be _____$°$.

_____ lines in a plane never meet.

When three parallel lines are intersected by a transversal, _____ pairs of corresponding angles are formed.

When two parallel lines are intersected by two transversal then _____ pairs of alternate angles are formed.

The internal bisectors of co-interior angles are _____ to each other. (perpendicular/parallel)