Answer:

Step-by-step explanation:
Speed on going = 600 miles per hour
Let t be the time om going
So, Distance = 
Distance = 
Speed on return = 480 miles per hour
The round trip took 18 hours.
So, Time on returning = 18-t
Distance = 
Distance = 
Distance will remain same on going and returning
So, 
Hence equation can be used to determine the time for each leg is 