The first statement CA || DB , E is midpoint is GIVEN to you. That is the reason that statement can be made. It is GIVEN.
The second statement I would make is that ∠ACE = ∠DBE and ∠CAE = ∠EDB because Alternate interior Angles of parallel line CA || BD. You can also say ∠DEB = ∠CEA due to vertical angles being equal.
The third statement should be that AE = ED because E is the midpoint of AD.
The fourth statement is that the triangles are congruent, this is because ASA . Angle-Side-Angle are equal.
