You were not driving for 12 hours.
<em><u>Explanation</u></em>
Distance to the vacation spot is 1500 miles and you estimate that you drove an average speed of 50 mph.
<u>Relationship between distance, speed and time</u> is.......
So, the <u>number of hours you drove</u>
Given that, including rest stops it’s takes you 42 hours to get to the vacation spot.
Thus, the number of hours you were not driving