Is a traveler's Maghrib prayer after 'Isha valid? And what are the conditions for combining prayers while traveling?

It is permissible for a traveler to combine two prayers if the distance is approximately 80 km (a distance that permits shortening prayers), and the journey is permissible, and the intention is to stay for four days or less. It is stipulated that one should not begin to avail of the concessions until leaving their city, and that the two prayers be performed consecutively (according to the majority of scholars), and that there be a proper sequence between the combined prayers (such as Dhuhr before Asr, and Maghrib before Isha).