A great approach to solve this is just to make a table with time in one column and corresponding distance in the other column. Add 2 miles every time you add 20 minutes, since the speed is constant. Here:
TIME (DURATION OF TRAVEL). DISTANCE COVERED IN THAT TIME
(MINUTES) (MILES)
20 2
40 4
60 6
80 8
80 minutes = 1 hour + 2 minutes, which implies ______ miles. See the table!