You were not driving for 12 hours.
Explanation
Distance to the vacation spot is 1500 miles and you estimate that you drove an average speed of 50 mph.
Relationship between distance, speed and time is.......
[tex]distance=speed*time\\ \\ time=\frac{distance}{speed}[/tex]
So, the number of hours you drove [tex]=\frac{1500}{50}hours= 30 hours[/tex]
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 [tex]=(42-30)=12 hours[/tex]
