You can
put this solution on YOUR website!They average 24 mph on way in at x distance and y time.
They Reutrned at 18 mph on way out at x distance and y time.
Time = distance/speed.

Commom multiple = 72

7x=504
x=72
72/24 = 3
72/18 = 4
3+4=7 (it checks)
Hence, the total distance travelled was 72 miles, for 24mph the time taken was 3hours and for 18mph the time taken was 4hours.
Paul.