What reason should kamal add to all of the question marks in order to completer the proof

The answers is alternate interior angles.

Step-by-step explanation:  First of all, the questions marks given in the figure are renamed in the attached figure as (a), (b), (c) and (d).

For (a): Since AC is parallel to A'C' and A'D is a transversal for these two parallel lines, so, ∠CDB' = ∠B'A'C', because these are alternate interior angles.

For (b): Since BC is parallel to B'C' and A'B' is a transversal, so ∠BEB' = ∠A'B'C', because these are alternate interior angles.

For (c): Since AB is parallel to A'B' and AD is a transversal, so ∠BAC = ∠CDB', because these are alternate interior angles.

For (d): Since AB is parallel to A'B' and BE is a transversal, so ∠ABC = ∠BEB', because these are alternate interior angles.

Thus, all the questions marks are the reasons that the given angles are equal because they are alternate interior angles.

3 Passengers per car

Step-by-step explanation:

We assume there are the same amount of passengers per car so we do:

9/3 = 3