Answer:
6 2/3 hours
Explanation:
We assume the time of interest is the total time spent on the main road and side road.
In each case, ...
... time = distance/speed
On the main road, ...
... tmain = s/v
On the side road, ...
... tside = (2s)/(v -2)
Then the total time spent is ...
... ttotal = tmain + tside
... = s/v + (2s)/(v -2)
For s=10 and v=6, this is ...
... ttotal = 10/6 + 2ยท10/(6 -2) = 5/3 + 20/4 = 5/3 + 5 . . . . hours
... ttotal = 6 2/3 hours