The puzzle was relatively simple and many of you sent the correct answers. The first one to send the correct answer was Girish Tutakne, and the first child to send the correct answer was Anshi from Gurgaon. Well done Anshi! I also got a correct answer from Shray from New Jersey.
I am reproducing the answer from Girish:
In a return trip, distance traveled up and down are equal, because uphill in one direction becomes downhill in the other. As downhill speed is double that of uphill, time spent downhill be half of the time spent while driving uphill. Therefore, out of 6 hours, 4 hours are spent driving uphill and 2 hours driving downhill. Therefore, the total distance back and forth is 60×2 + 30×4 = 240 miles ==> distance between the two places is 120 miles.
Hope you enjoyed the puzzle!