It turns out that the company Aeroflot has made two flights, the first one has flight time of 1 hour 48 minutes, the second one - 2 hour 6 minutes, The total duration of flights turns out (108 + 126) = 234 minutes, but not is 216 minutes (as it is specified in "correct result ").
Misunderstanding is caused by insufficient studying of the description and the scheme of database. Trip table represents the schedule of flights, which are carried out daily.
The information on flights of passengers contains in Pass_in_trip table. Let's look what flights of the company with id_comp=2 have been carried out:
SELECT pt.trip_no, date, time_out, time_in
FROM pass_in_trip pt
(SELECT trip_no,time_out,time_in FROM trip WHERE id_comp=2) t