Answer:
5 hours
Step-by-step explanation:
Time taken for trip : t + 1
Time taken for return : t
Avg. speed (trip) : 256 km/h
Avg. speed (return) : 320 km/h
The distances covered on both trips are equal.
⇒ Distance (trip) = Distance (return)
⇒ Speed (trip) × time (trip) = Speed (return) × time (return)
⇒ (256)(t + 1) = (320)(t)
⇒ 256t + 256 = 320t
⇒ 64t = 256
⇒ t = 4 hours
<u>Time (trip)</u> = t + 1 = 4 + 1 = 5 hours