speed = distance/time
total time is 8 hours
outgoing speed is 160 km per hour,
so time = d/160
returning speed is 240 km per hour,
so time = d/240
d/160 + d/240 = 8
3d/480 + 2d/480 = 8
5d/480 = 8
5d =480 (8)
5d = 3840
d=3840/5
d=768
answer: so the distance is 768 km