Where does it say you only have 2 hour? You can average 60 mph for 10 hours right? There is no reason why you can not drive faster for 1 more hour and have an average of 60mph. Maybe I am reading it wrong.
ur not reading it wrong ur just not getting it
the town is 60 km away and for 1 hour you travel 30 kph so ur halfway. the only way to get sixty would be to travel for another hour at 90 kph but if u did that you would 60 miles past the town and if u slow don then the average speed would be less then 60 so it is impossible