They travelled 3 and 5/6 miles, then drove 2 and 2/6 more the next day. To find the total, you must add them up. So...

They travelled for 6 and 1/6 hours, or 6 hours and 10 minutes.
The first graph doesn’t show it
Decomposing a fraction means to take it apart, the most basic way to decompose a fraction is to break into unit fractions, thats all I know so far