https://sql-academy.org/ru/sandbox
1)
SELECT *
FROM Trip
JOIN Company ON trip.company=company.id
2)
SELECT plane AS "самолет",
       town_from AS "город вылета",
       name AS "название"
FROM Trip t
JOIN Company c ON t.company=c.id
GROUP BY
3)
SELECT name AS "название", COUNT(t.id)
FROM Trip t
JOIN Company c ON t.company=c.id
JOIN Pass_in_trip p ON t.id=p.trip
GROUP BY name
4)
SELECT *
FROM Trip t
JOIN Company c ON t.company=c.id
JOIN Pass_in_trip p ON t.id=p.trip
5)
SELECT *
FROM Trip t
JOIN Company c ON t.company=c.id
JOIN Pass_in_trip p ON t.id=p.trip
JOIN passenger pr ON pr.id=p.passenger